Hi there --
If your project is not too big and you're willing to share it, I'd be curious to try to track down the root cause so we can fix it. However, there may also be a remedy to the situation that's a little easier (and faster to get you up and running again).
If you hold shift while opening the project, it will clear out temporary UI/selection state data which can often get around errors of this sort. If you would like to share your project to help pin the bug, quit Ch and just zip up the project folder. If not, though, and you just want to get back to it, that's cool, too.
Hopefully the trick of holding shift to reset the UI state data will get you back to good.
Thanks! -- Dan Tull
The shift hold on opening the project seemed to work at first, but then the issue reoccurred. I was able to go back several days and retrieve a workable version of the project (keeping my fingers crossed!). I'll will post back here if I have further issues. I believe the issue occurred after I deleted some assets/scenes I didn't need anymore and was cleaning up the project. I had duplicated a rigged image so I could rig it differently for each scene and that seemed to bog down my system when I made changes to the asset in Illustrator.
Thank you for offering to remedy the concern!
If you do find more info on what is causing the error, definitely post more details. I'd love to pin this so we can get it fixed. Glad you found a way to proceed, in any case.