I'm having occasional situations where clips become in-audible on their own as if they were muted but they are not.
 
The worst case scenario is when I'm in the middle of editing take lanes (say 5 lanes with 10 clip slices in each) and some of the clips suddenly look slightly lighter (but not as light as muted clips) and become silent.
 
Another scenario (when I'm not in take lanes) is when a track will play it's own original clips but won't play any other clip I drag to it. Again the clip turns silent (and the track is not locked or muted).
 
Once or twice a clip came back to life after I tried a few things but it doesn't seem to be a specific thing I did because everything I try with other clips/tracks fails.
 
I'm using Platinum with the latest update on a i5 Win 10 machine with 16 gb ram and SSD drives.

I guess I'm running into the same thing - I had described it differently as "notes greyed out", but you're describing it better. 

The behavior of clips in lanes is very tricky, and different if you recorded them in Sound on Sound or Comping mode.  The safest way to do multiple passes is Sound on Sound and store the takes in separate TRACKS.  Then you end up with tracks that will behave normally.  Just wait til you try and quantize or god forbid apply a region effect to a take-laned audio vocal, or double click on a midi take to open it in piano roll and it appears instead in the Audio view completely blank.  There are only very specific things I use take lanes for...because I realized only recently that they are for specific purposes and do not necessarily function like normal tracks.  I am not up to speed on it yet...but have run into those problems you both are having. 

Thanks - that may very well be the cause for me. I have dragged melodyne onto a vocal made up of take lanes, and down am sure to bounce to a separate track these days! 

herbroselle
I guess I'm running into the same thing - I had described it differently as "notes greyed out", but you're describing it better. 

Just to clarify....  is the whole clip greyed out or just the waveform? 

just the midi note.
 
Interesting - i had about 32 measures of a song done, and stepped out for 2 hours. When i came back, they were greyed out. So save often!!

herbroselle
just the midi note.
 
Interesting - i had about 32 measures of a song done, and stepped out for 2 hours. When i came back, they were greyed out. So save often!!

Assuming you're using a USB interface, ake sure your USB ports aren't set to save power by turning off after inactivity. 

Sometime,I don't know why the mute button shifts on automated,then the clip is muted but one cannot see it .When this happens you have to go back in the normal mute behavior.
So from where I am when clips are going silent,I right click on the mute button and sometime find the answer.