Got to Settings Apps and see if MS Flight Simulator is installed on your C: drive.
Optional: Under Advanced Options, Click Repair. Caution, not Reset.
This proves to me that it is installed.
Now, go to back under the MS Flight Simulator App and click “Uninstall”.
Then, go to MS Store/Xbox and download it again.
When the install screen appears, click the location box and tell it to install on your H: drive.
It will download the initial 1.3GB to the C: drive.
If it sees your H: drive and the files it expects to be there, it will not download
the Installed Packages again. (130 GB).
If it does not see the H; files, it will download them again to H: