This is occurring for me as well, latest crash dump sent: 2021-08-11_08.14.14_1cb31cfd62cca6459047718a04a7579e
I have seen this a number of times previous run throughs & you have a similar thread on these forums which is marked as resolved, but does not appear to be.
I have re-run the mission a number of times and is 100% repeatable. Have tried manual combat, auto resolve, completing with just my party & with multiple parties, and 3 of 4 map locations in the general area.
Validation of files shows no issues.
I find these quests moderately annoying as whole, generally uninspiring with the only challenge being that they send you to the four corners of the map at the detriment of any ongoing wars you may have going on. Last run through I did was a sandpit game due to avoid these quests, but on restarting again I decided to give it another try.
In this case I ditched a siege on a western empire castle to run full speed to the furthermost North East of the map to destroy a bandit camp, only to have to immediately dash all the way back to the mid-west to kill bandits on another conspiracy quest, which then crashes on me.
Running backwards and forwards across the map continuously to complete relatively menial tasks is not exactly inspiring for your main character when compared to say establishing the start of your new kingdom which is probably why I tend to restart so many times.
