[2022] Game crashes right after loading save file

Was this game started under the 1.7.x patches? or some earlier one?

Can you start and play a new test campaign now alright?  

I'm not quite sure of your answer; what game version was that save game you put in your OP here started under? 1.6.x, or 1.7.x ?

Can you start and play a new test campaign now alright?  

Ah, okay, that would explain it! If you have a save game from that campaign which has NOT been updated and written by a later patch, you should revert to 1.5.x in the Steam Betas tab to finish that campaign.  

You cannot, I'm sorry to say - Microsoft do not provide any facility for us to distribute older or alternate game versions, unlike Steam.

Your only way to play that save would be to buy the game from Steam, OR use family Sharing to borrow that game from anyone you know who has it.

Sorry about that!