diff --git a/web/app/assets/javascripts/react-components/PopupMediaControls.js.jsx.coffee b/web/app/assets/javascripts/react-components/PopupMediaControls.js.jsx.coffee
index 06e7d6535..b73105757 100644
--- a/web/app/assets/javascripts/react-components/PopupMediaControls.js.jsx.coffee
+++ b/web/app/assets/javascripts/react-components/PopupMediaControls.js.jsx.coffee
@@ -89,11 +89,13 @@ mixins.push(Reflux.listenTo(MediaPlaybackStore, 'onMediaStateChanged'))
     context.JK.checkbox($loop)
 
     $loop.on('ifChecked', () =>
-      console.log("@props", @props)
-      MixerActions.loopChanged(@props.backingTracks[0].mixers.mixer, true)
+      logger.debug("@props", @props)
+      # it doesn't matter if you do personal or master, because backend just syncs both
+      MixerActions.loopChanged(@props.backingTracks[0].mixers.personal.mixer, true)
     )
     $loop.on('ifUnchecked', () =>
-      MixerActions.loopChanged(@props.backingTracks[0].mixers.mixer, false)
+      # it doesn't matter if you do personal or master, because backend just syncs both
+      MixerActions.loopChanged(@props.backingTracks[0].mixers.personal.mixer, false)
     )
 
     @resizeWindow()
diff --git a/web/app/assets/javascripts/react-components/SessionBackingTrack.js.jsx.coffee b/web/app/assets/javascripts/react-components/SessionBackingTrack.js.jsx.coffee
index f94f96ff4..049234abd 100644
--- a/web/app/assets/javascripts/react-components/SessionBackingTrack.js.jsx.coffee
+++ b/web/app/assets/javascripts/react-components/SessionBackingTrack.js.jsx.coffee
@@ -40,7 +40,7 @@ MixerActions = @MixerActions
       "backing-track" : true
     })
 
-    pan = mixers.mixer.pan
+    pan = if mixers.mixer? then mixers.mixer?.pan else 0
 
     panStyle = {
       transform: "rotate(#{pan}deg)"
diff --git a/web/app/assets/javascripts/react-components/SessionJamTrack.js.jsx.coffee b/web/app/assets/javascripts/react-components/SessionJamTrack.js.jsx.coffee
index fb5ce656b..7cbe3f6d6 100644
--- a/web/app/assets/javascripts/react-components/SessionJamTrack.js.jsx.coffee
+++ b/web/app/assets/javascripts/react-components/SessionJamTrack.js.jsx.coffee
@@ -40,7 +40,7 @@ MixerActions = @MixerActions
       "jam-track" : true
     })
 
-    pan = mixers.mixer.pan
+    pan = if mixers.mixer? then mixers.mixer?.pan else 0
 
     panStyle = {
       transform: "rotate(#{pan}deg)"
diff --git a/web/app/assets/javascripts/react-components/SessionMasterMix.js.jsx.coffee b/web/app/assets/javascripts/react-components/SessionMasterMix.js.jsx.coffee
index 51a9be63a..8227a6e06 100644
--- a/web/app/assets/javascripts/react-components/SessionMasterMix.js.jsx.coffee
+++ b/web/app/assets/javascripts/react-components/SessionMasterMix.js.jsx.coffee
@@ -8,6 +8,6 @@ MIX_MODES = context.JK.MIX_MODES
       <SessionMasterMyTracks mode={MIX_MODES.MASTER} />
       <SessionMasterOtherTracks mode={MIX_MODES.MASTER} />
       <SessionMasterMediaTracks mode={MIX_MODES.MASTER} />
-      <SessionMasterCategoryControls />
+      <SessionMasterCategoryControls mode={MIX_MODES.MASTER} />
     </div>`
 })
\ No newline at end of file
diff --git a/web/app/assets/javascripts/react-components/SessionMetronome.js.jsx.coffee b/web/app/assets/javascripts/react-components/SessionMetronome.js.jsx.coffee
index 41bc7a8bf..5c34c0357 100644
--- a/web/app/assets/javascripts/react-components/SessionMetronome.js.jsx.coffee
+++ b/web/app/assets/javascripts/react-components/SessionMetronome.js.jsx.coffee
@@ -31,7 +31,7 @@ MixerActions = @MixerActions
       "metronome" : true
     })
 
-    pan = mixers.mixer.pan
+    pan = if mixers.mixer? then mixers.mixer?.pan else 0
 
     panStyle = {
       transform: "rotate(#{pan}deg)"
diff --git a/web/app/assets/javascripts/react-components/SessionOtherTrack.js.jsx.coffee b/web/app/assets/javascripts/react-components/SessionOtherTrack.js.jsx.coffee
index c148cf198..e0148d343 100644
--- a/web/app/assets/javascripts/react-components/SessionOtherTrack.js.jsx.coffee
+++ b/web/app/assets/javascripts/react-components/SessionOtherTrack.js.jsx.coffee
@@ -13,7 +13,9 @@ MixerActions = @MixerActions
 
     muting = $(e.currentTarget).is('.enabled')
 
-    MixerActions.mute([this.props.mixers.mixer, this.props.mixers.oppositeMixer], muting)
+    mixers = if this.props.tracks.length > 0 then this.props.tracks[0].mixers else {}
+
+    MixerActions.mute([mixers.mixer], muting)
 
   render: () ->
 
diff --git a/web/app/assets/javascripts/react-components/SessionRecordedTrack.js.jsx.coffee b/web/app/assets/javascripts/react-components/SessionRecordedTrack.js.jsx.coffee
index 8034ae4cb..2d652a191 100644
--- a/web/app/assets/javascripts/react-components/SessionRecordedTrack.js.jsx.coffee
+++ b/web/app/assets/javascripts/react-components/SessionRecordedTrack.js.jsx.coffee
@@ -40,7 +40,7 @@ MixerActions = @MixerActions
       "recorded-track" : true
     })
 
-    pan = mixers.mixer.pan
+    pan = if mixers.mixer? then mixers.mixer?.pan else 0
 
     panStyle = {
       transform: "rotate(#{pan}deg)"
diff --git a/web/app/assets/javascripts/react-components/helpers/MixerHelper.js.coffee b/web/app/assets/javascripts/react-components/helpers/MixerHelper.js.coffee
index 403a9c202..065782ab9 100644
--- a/web/app/assets/javascripts/react-components/helpers/MixerHelper.js.coffee
+++ b/web/app/assets/javascripts/react-components/helpers/MixerHelper.js.coffee
@@ -505,6 +505,10 @@ MIX_MODES = context.JK.MIX_MODES;
     mixers = if mixMode == MIX_MODES.MASTER then @masterMixers else @personalMixers;
 
     for mixer in mixers
+      unless mixer?
+        logger.debug("empty mixer: ", mixers)
+        continue
+
       if mixer.client_id == clientId
         for groupId in groupIds
           if mixer.group_id == groupId
@@ -746,6 +750,7 @@ MIX_MODES = context.JK.MIX_MODES;
 
     if mixer?
       context.JK.VuHelpers.updateVU3(mixer, leftValue, leftClipping, rightValue, rightClipping)
+
     ###
     if mixer
       if mixer.stereo # // stereo track
diff --git a/web/app/assets/javascripts/react-components/mixins/SessionMyTracksMixin.js.coffee b/web/app/assets/javascripts/react-components/mixins/SessionMyTracksMixin.js.coffee
index 937102629..3af65b420 100644
--- a/web/app/assets/javascripts/react-components/mixins/SessionMyTracksMixin.js.coffee
+++ b/web/app/assets/javascripts/react-components/mixins/SessionMyTracksMixin.js.coffee
@@ -12,18 +12,18 @@ context = window
 
     if session.inSession()
       participant = session.getParticipant(@app.clientId)
-      photoUrl = context.JK.resolveAvatarUrl(participant.user.photo_url);
-
-      chatMixer = mixers.chatMixer
-      chat = null
-      if chatMixer
-        chat =
-          mixers: chatMixer
-          mode: @props.mode
-          photoUrl: photoUrl
-
 
       if participant
+        photoUrl = context.JK.resolveAvatarUrl(participant.user.photo_url);
+
+        chatMixer = mixers.chatMixer
+        chat = null
+        if chatMixer
+          chat =
+            mixers: chatMixer
+            mode: @props.mode
+            photoUrl: photoUrl
+
         name = participant.user.name;
 
         for track in participant.tracks
diff --git a/web/app/assets/javascripts/vuHelpers.js b/web/app/assets/javascripts/vuHelpers.js
index 4a83917ff..e2173f6dd 100644
--- a/web/app/assets/javascripts/vuHelpers.js
+++ b/web/app/assets/javascripts/vuHelpers.js
@@ -217,9 +217,6 @@
 
             var fqId = this.createQualifiedId(mixer)
 
-            if(mixer.group_id == 13) {
-                logger.debug("mixer", mixer)
-            }
             var registrations = this.registeredMixers[fqId]
             if (registrations) {
                 var j;