Yes, I also tried starting a new game, but I still have the same problem.
1 I summon the NPC and everything is ok.
2 I save the game.
3 I reload and the game crashes.
Doing some experiments I discovered that the game crashes because of his hair/horns (they become like a kind of yellow ray or like a kind of wooden board), in fact by putting a random wig on the NPC the game stopped crashing.
I thought there was some incompatibility with the ''gate of sovengarde'' collection, but I have another npc with the same hair and it has never given me problems. So I think my game for some reason can't load that npc hair and horns.
The crash logger give me this:
unhandled exception "EXCEPTION_ACCESS_VIOLATION" at 0x7FF90817E0BB nvwgf2umx.dll+02EE0BB test byte ptr [rbx+0x228],
0x04 Exception Flags: 0x00000000 Number of Parameters:
2 Access Violation: Tried to read memory at 0x00003DD85568