Don't know what I did, but one of my audio tracks, consisting of a bunch of separate clips, has grayed out, and I can't edit anything in it. The project has numerous audio tracks, this is the only one this happened to. The clips are dark gray, and a red Gain envelope sits on top of them (which I didn't add). I'd been doing a lot of copy paste of excerpts from clips in other tracks. Somehow I froze up that track. The lock and freeze options are not selected. I turned them on and back off to try and reset it, to no avail. What did I do?