As I recommended to the OP, if you have tried just about everything else, check the bug thread about MSFS (incorrectly) loading CODECs from other installed software (e.g. CaptureOne photo editor). It appears even other software installed on the PC can reveal MSFS coding bugs. This thread also gives instructions on how to see what DLLs the MSFS process is loading. Good luck!
https://forums.flightsimulator.com/t/bug-logged-ctd-caused-by-capture-one-20-codec