Question ProBuilder 3 -> 4 upgrade breaks UV layouts

Hello, fellow ProBuilders! I'm running into a strange issue when upgrading from 3.0.9 -> 4.5.0: after upgrading, some of my UV layouts are broken. Specifically, the UV islands appear to be correct but are offset by a seemingly arbitrary amount. (I can't see any rhyme or reason to it.)

Note that I'm also trying to upgrade from Unity 2018.4 to 2109.4 along with this, which also includes an upgrade of .NET. I have tried upgrading in a different order (Unity first vs ProBuilder first), but all scenarios result in the same broken UV layouts.

Can you think of any potential pitfalls or things to watch out for with this upgrade? I swear I've done this exact same upgrade in another project in the past, I'm not sure what the difference is in this case.

Thanks in advance,
Adam

 

Please understand...with any software/systems you use for your project, settle on 1 version for the life of the project (dont update or change ANYTHING), that goes for Unity, Probuilder, or anything you plan to use in your project...