Crossfire on Mac Pro 2013

EDIT:
I must have missed enabling VSync, but that was it. Leaving this up in case anyone else runs into the same issue!

ORIGINAL:
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Hey guys,

You fine folks might or might not be able to help me, but I have a question about fairly old hardware.

I have a Mac Pro 2013 with dual AMD FirePro D500s with 3GB of VRAM each, dual boot with BootCamp Win 10 Pro.

I had CrossFire working previously after following the instructions from fellow D3 players on this forum and reddit, but then had to reinstall Windows. I have followed all of the same steps (running D3 32-bit client, etc) and it just will not use the second GPU. Performance-wise it just does not run very well even at 1080p with one GPU.
Did Blizzard update the game recently? Because this was working a matter of weeks ago no problem.

Latest Windows 10 ver, BNet/D3 ver, and same version AMD drivers I had previously (not newest; newest cause other unrelated issues…thanks amd)
Please let me know if you guys have any advice!

SPECS:

WIN10 PRO
Intel XEON 6-Core 3.5GHz
32GB ECCRAM
Dual AMD FirePro D500 (6GB RAM TOTAL)