I've been playing D2:DC the last few days, and had been running with multicore/lockstep on, and I was getting the infinite load in about 10% of cases. This was in the original part of the game.
Without starting a new FoV campaign I just went into the expansion from the savegame of my ED game. Suddenly I was getting the infinite loading screen at slightly over 50% of all transitions. It was maddening.
So I ran the 4GB patch, turned off VSync, disabled and re-enabled multi-core/lockstep, disabled bloom and depth of field (those just from personal choice more than tech).
And now it's fine again on Win 10, 64 bit. I had intermittent choppiness with and without VSync before, but after the 4GB patch it's completely smooth.
Haven't had a transition issue since last night. Here's hoping that finishing of FoV today won't see another.