The issue is back for me too... And the "close tabs and restart C2" thing isn't working for me anymore...
I noticed a few other things. The affected items still have issues if you copy paste to another layout or project. When webgl is acting funny in C2 I no longer see a selectbox (when you click and drag). And selections are no longer highlighted; with a box, and the size and angle handles don't show anymore (but if you hover in the right place your mouse cursor will change). Even after removing the effect there is still an issue.
Some things are visually warping, and others are disappearing. For the things warping, I do not have a warp effect, only tint effect. For the things disappearing, they are not moving to a different z order or layer.
I think I never ran into this before because this is the first time I've done this much with webgl effects. Specifically I'm using the tint effect a lot. Not everything with a tint effect is having issues, and it's not the same objects having issues each time. Depending on the zoom level and position of the layout in view, sometimes I can see the objects as "normal" (including the tint currently applied). The value of the effect options doesn't seem to matter either.
I copy/pasted a few of the items having issues into a new project and attached the capx to this post. For me the issue currently exists in this capx as well. - I can't seem to attach this file, I'm getting a server error from the forum. I'll see if I can host somewhere else and post a link. - link here
Again, I don't think it's a video driver thing as both of my computers are having the issue; they have completely different hardware and video drivers (Intel and AMD).
This has definitely become a big enough issue that it's slowing down development. I'm not sure what else I can do at this point, I have no "workarounds" left, and I can't see some objects in the layout.