I first bought this game way back in the 90's in a Warhammer 4-pack (Chaos gate, Shadow of the horned rat, Final liberation, Dark omen - Still waiting for GOG to get this one)
Never did manage to finish the game due to random issues where I kept losing my saves

Then GOG got their hands on it and I immediately picked it up but couldn't get it to run so it collected dust in my inventory until recently.

Pulled the game up again after the GOG galaxy update and to my surprise, it was working!

I've had no issues at all on my Win10 machine until the mission where you are to enter the cathedral and destroy the warpgate (3 part mission after destroying the fortress gates and shutting down the shield generator)
The first time you get to use Terminators.

I've tried many times now but the game always CTD on chaos turn 1 right after the 2nd chaos terminator moves. Every time :(

Any advice on what I can do to fix it? I already tried compatibility settings, but that didn't affect anything.

Just for some further information:
My PC:
Windows 10 64bit
AMD threadripper 1900x
16GB ram
nVidia GTX 970

Marine force:
5 Terminators: power sword, assault cannon, 2x power fist, 3x chainfist, 4x storm bolter
5 Tac squad: Master crafted bolter, plasma gun, rest is default
4 assault squad: purifier flamer, liberator axe, conciliator sword, 3x plasma pistol, power sword, power axe
librarian spells: hellfire, lightning, displacement

First player turn:
No issues

Chaos first turn:
a squad of 5 world bearers exit the cathedral, some of their guys get killed by overwatch, about a dozen cultists move, chaos terminator 1 moves, chaos terminator 2 moves, then crash to desktop

Every time, no matter how I play my first turn.

And I have an update

Excited to say I had a saved game right after the previous mission was completed so I repicked and re-outfitted my squads and was just now able to complete the destroy the warpgate mission without issue.

Must have been an error in generating the mission the first time.