Unfortunately, I can’t answer your direct question, but if you’ll allow me to butt in and answer an unasked question…
You should not be running MSFS on an HDD. (Meaning a physical hard drives with spinning magnetic media, which I call a “spinner”.) In fact, nothing MSFS related should be put on a spinner, not add-on files, not cache files, not anything. It’s just not built for the (slow) speed that spinners have compared to SSDs.
In fact, going even further, the only place spinners should be used in 2020 given all the big picture price reductions on SSDs, etc., is for a local drive that stores (for viewing, never for editing) video and movie files, on inside of a NAS for nearline storage. They are performant enough for those uses, but really nothing else any more.
Now, with apologies for the thread hijack, back to your regularly scheduled programming…