Btw, after you get this, it’s possible that DF doesn’t work on launcher 4.12 version either. If you go to:
C:\Users<username>\AppData\Local\UnrealEngine
and delete all cached files there (whole dir), you get it working again, but I couldn’t find any way to make the custom builds still work. Deleting that folder (not 100% if you needed to delete some intermediate or saved folders on your projects as well), DF works again on binary builds. Since logs don’t tell anything special, I’m bit clueless where I should look next to solve this. This is preventing me from using any source builds atm.