Do you have any MSStore addons, if so, have you tried the sim in Safe Mode?
If the issue is still occurring, you could try a re-install.
If you are going that route, cut and paste your community folder outside of the MSFS file structure.
Uninstall the sim from the Windows start menu, (right click on Microsoft Flight Simulator and select uninstall).
Delete all remaining folders after the uninstall.
Restart PC and install sim.
After the sim is up and runing, if all is OK, add your addons back to your new community folder a few at a time, trying the sim after each batch for this issue, until you have them all back in.