Hey guys , I had this issue since I got my new PC and I tried everything
from deleting the decompressing files and redownload them to downloading the whole sim again but it stuck at decompressing phase. But at the end I found out something really strange ! It was all because of my ram frequency.When I turned ON XMP/DOCP on BIOS and put RAMS on max frequency (mine was 6600MHZ) , Still I would get stuck at decompressing phase but when I lowered my ram frequency from 6600MHZ to 6400MHZ everything worked fine !
It’s really odd for MSFS having these kind of bugs but if you’re having these kind of issues I recommend you doing the same thing and see if it works for you.
I hope my comment helps you !
aaMasih