Hi,
I’ve bought the premium deluxe edition from steam. After 40hrs of playing with pretty much no bugs, tonight after 2 crashes on the loading screen I’ve tried to check integrity files on steam. Not sure what caused the problem but as soon as I restarted the game, the installation folder was empty, it started again to download 110gb of game. Now I understand some bug etc… but this is crazy. I’m on win 10 64bit with all the updates, latest nvidia drivers (gtx 1080ti).
Just incredible. 
Yes, this is a thing with the Steam version. Have a look at the Steam forum and you will see a lot of posts about this. Sorry for the 100GB download again.
I understand but it should be fixed by asobo, I never had something like this on steam, ever. It’s quite a huge bug.
Same thing happened to me through the Microsoft Store. And the download of the latest version was well in excess of 110gb as at the 75gb mark it reverted to 45gb in the progress bar though no files were deleted and it still downloaded to the theoretical 110gb. The download data from my ISP bears out that around 140gb was transferred. This whole download process is shambolic. Not everyone has limitless download capacity or fast download speeds.
Something similar happened to me except I signed out in game. When I tried to restart the game steam keeps trying to re-download the entire game despite 120 odd gig of data in the game folder.
I feel your pain. Verifying the files resets everything to the way Steam initially had it. And since Steam only downloads the initial launcher and not the actual 100GB data… that’s a recipe for frustration.
If you look at Zendesk, there are actually guides on how to verify the integrity of MSFS for Steam and MS Store. I didn’t know if it was the same case with the MS version (cheers Sledge, mine is from Steam), but until this gets done the proper way, there should be a big disclaimer warning folks that they will risk downloading the entire game again. Please report it.