When you repro’d it yourself, was your GameInstance referencing the radioactive class?
That seems to be the only way to break it for me. I can have all manner of other classes referencing something that creates CommonUI widgets without issue. If you’ve found another way though, do let me know - I am now extremely untrusting of this whole plugin and will be walking on eggshells for the rest of my development. 
In my proejct, I almost never have the GameInstance reference other classes - it primarily acts as a store of data that other classes read/write from, so avoiding this specific interaction is totally possible for me. I worry there are other landmines though.