[brazen1]

I use .iso for both 4K and 3D files on MPC-BE x64. On this sytem, if the "Stereoscopic 3D" box is not checked, I don't get 3D. If it is checked, MPC-BE crashes out playing a 4k iso. The display flashes HDR then blinks back and MPC-BE is gone. It's not frozen and there's no error messages, it's just gone. This happens outside of Kodi as well is launching from Kodi but I believe I can use Kodi playercorefactory or mpc-be.bat to fix.
 

3D stereoscopic should always be enabled.  All players know how to handle 2D and 3D plus madVR has settings to force the GPU and global settings appropriately.  MPC has an additional d/l for 3D included in it's installer as well.
MPC is crashing because you are not mounting your iso's.  The player does not have an internal mounting mechanism.  W10 does but you would have to manually mount and expand the iso and play using index.bdmv which I do all the time for testing.  This is why I created .bats to introduce the external mounting program Virtual Clone Drive for the players called by the PCF.xml.  None of this is anything new and is already included in the guide so you don't have to solve and create anything that doesn't already exist.  I don't know why KODI continued crashing for you when exiting an external player?  This was resolved in the early alpha releases of 18.1 a long time ago.  Your setup before upgrading recently must have been wonky for some reason(s).  If you haven't kept up with the thread in a while, your best bet for drivers is 385.28 instead of newer ones.  This could also be contributing to the errors you are experiencing.  Outside of what I've written, I've no other ideas for you.  Everything is working pretty good here and has been.