Like others, I was experiencing CTDs with no error message when using Offline AI traffic, even at low settings.
Eliminating other possible causes did not help (Community folder = empty, SimConnect = no connections, unplugged device drivers = cleaned out, NVidia driver = best working version 446.14, hardware overclocks = none).
Like others, I noticed that these CTDs were semi-reproduceable, in that if I repeated the same flight (same flight plan and timings), then the CTDs would occur consistently at more or less the same spot.
This led me to believe that the stock Offline AI traffic BGL file must be at fault.
I used AIFP3 to validate the traffic BGL file, and sure enough it identifies hundreds of data issues in the AI flight plans, including legs with missing departure / arrival airports, legs with impossible flight plan altitudes, etc.
Due to its size, I split the stock traffic BGL file into 2 separate traffic BGL files (1 for commercial, 1 for GA), and corrected / removed any AI flight plans with invalid data. I then disabled the original stock traffic BGL file, and added the 2 new traffic BGL files as add-ons in the community folder.
After 1 day of testing, this seems to have cured all CTDs when using Offline AI traffic, even with traffic levels both set to 100%.
I will do some further testing and if stable, I can upload my modified traffic BGLs as a community add-on, if that would be useful.
In the meantime, if you would like to try the workaround for yourself, then you just need to correct and replace the stock BGL file using AIFP3, as described above.
AIFP3: Stuff 4FS dot com
Stock traffic BGL file: \fs-base-ai-traffic\scenery\world\traffic\trafficAircraft.bgl