I saw on steam where the developers requested data on people having this problem.  I went to play the mission that I was having the crash on (had completed 2 of the 3, and was having crash on the 3) and noticed I had 3 new missions (ORDOS XENOS missions).  I played and was able to complete all three with no crashes.  Below is the information I had gathered.

1. Did the crash appear on a Seasonal or non-Seasonal character, maybe both?

Reply: Seasonal

2. On what language are you playing?

Reply: English

3. How often does the problem occur?

Reply: Repeatable, have attempted 6 times

4. What class are you playing with?

Reply: Psyker - Empyreanist

5. What is your account+character name?

Reply:  account name is afngary; character name is Mandor

6. Did the crash appear to all of your characters?

Reply: No

7. In case of a Seasonal character, did you notice seasonal anomalies prior to the crash?

Reply: No

8. Can you name an item which was probably the source of the problem and if you unequipped it, the crash no longer appeared?

9. Please tell us the game mode, the enemy type and the map type if you can recall them.

Reply:  ORDOS XENOS mission; dark elder; rocky with platform to platform pathing.

10. Any further note you may found and can be important.