@ Myerz, for what it's worth: I had similar hangs as you describe in another thread.
Also - installing V12 seemingly "backfired" hangs into my ever so rock stable V11 last build so that I had to uninstall V12 - but all this has improved with the newest V12 486.
So, right now I am making all new projects with V12 486.
(seems to be a bad idea to change version in the middle of a project).
My experience with two different versions of VP is that I have to make sure that each uses a different location for the temporary files location. Also the prerendered and recorded files lcoation should be different.