My experience has been that when MSFS crashes to desktop attempting a manual cache, the next time the sim runs I am prompted with a dialogue box telling me the sim closed down unexpectedly and I have two choices “safe mode” or “continue with normal mode”.
Selecting “safe mode” disables all community folder items and marketplace purchases. This may allow for the manual cache to proceed as intended if “safe mode” is selected as the option.
The next time MSFS runs, provided the sim was closed normally, there should be no more prompt for this choice and the sim should launch as normal.