Why are my NLA editor clips grey and inactive?

Question

I've been using the NLA editor to compose an animation scene using character rigs.

It'd been going great until I opened the file and found the clips are all grey and the rig is no longer animated at all.

I can't figure out why the clips are grey and inactive?

This has happened once before, but only to a single clip among many other working clips. I fixed it by moving the greyed-out clip onto a fresh NLA track and it immediately became active again. No such luck this time.

I've attached two images below - One of a working editor and one when it's seemingly broken.

I know that for many people, the NLA editor is still quite a mysterious tool in Blender, so I hope somebody here has some experience with this issue.

Thanks in advance for any help.

Answer 1

I have the answer to this problem now, so I will explain in detail below for anyone else who needs to know.

Basically, it was a glitch caused when I created a new clip on a track above the other, but then deleted said clip.

There are three solutions to essentially ‘refresh’ your NLA clips. One of them should work.

1. Select the foundational clip (on the track at the bottom of the stack), take it into edit mode (tab key) and bring it back out again. That should refresh all the tracks and clips above it and essentially reactivate them.

2. Select the grayed-out clip, take it into edit mode (tab key), go into the graph edit (for said clip) and make sure all the curves (trans, rot, scale) are switched on (visibility). To do this, select all the curves, hold ALT and press P.

3. As a last resort, select on the track that has a grey-out clip on it, go to Add (in the NLA Editor) and select Add Tracks Above Selected. Next, select your clip, press G (to translate), press Y (to lock to the Y axis) and move your clip up to the newly created track.

I hope that helps.