I should also add that there might be something strange going on with using Undo (ctrl-z) that might be related. I have not been able to determine what the catalyst is for the work getting wiped out (it basically has been there until its not- and the lost work is generally on other parts of the model that I'm no longer focused on / visible in the viewport), but I noticed on more than one occasion that when hitting ctrl-z the system will actually revert more than just a single completed stroke- in some cases it will remove several strokes unpredictably. Just thought I'd mention this. ... View more

Hi Cyril (or other Adobe representative). I wanted to give an update on this. I am pretty certain that this is a bug. I have just spent additional time inspecting my geometry and UVs, ensuring their integrity and ensuring that there was nothing wrong with the model. I decreased the total number of UDIMs to 30 (from the original 40) in an effort to optimize my project even further for painting. I started a new project and used a black fill layer (with a mask- adding a paint layer effect to create the line work) to attempt to get my model painted. Once again, after finishing a few hours of work (and having successfully saved the file and reopening it more than once to test the stability of progress), I have just now noticed that once again, much of my work has disappeared. Test lines I added after making the recommended adjustment seemed to be saved overnight (with the application having been closed and reopened), but once again, after working on the file for a couple hours something within Painter once again deleted the majority of the painted lines. I am attaching a screenshot of a detail of the model that was painted and subsequently lost- I added red arrows to point out what portions of the strokes remain from the original work, and added dotted lines in red where there were originally lines that have now been lost due to this problem. Is there anything I can do to help further diagnose this problem? It's important that I finish this work, but I'm at a stopping point due to the unpredictability/instability of this issue. Please let me know what I can do to get this resolved- thanks!  ... View more

Thanks Cyril- I will give it a try! ... View more