Hi!
I have had this wierd problem some (long) time ago and now it reappeard all the sudden the other day. When I was editing the transients in a long audio clip the clip went all grey. No audio nor transients were visible any longer for that one clip in the Track View. The clip would play, though, as nothing were wrong.
Then I changed something (I don't recall what, it may have been just resizing the track or something else trivial) and poof! the visuals would come back. Yet after a little while they would re-disappear and it would take some poking-around to get them back.
Any one else experienced this lately? Any suggestions?