I’m now six patches in, and have never seen this. I think its a little clunky that you have to download from the MS Store first, but it has worked for me every single time.
I have no idea why so many people seem to have a problem with it, but I guess its a combination of things, like the Internet connection in your geographic location or speed, computer configuration, maybe more people using Steam have issues than MS Store purchasers.
People tend to omit a lot of information that might assist with working out what is going wrong. For example, your post tells me nothing that I might need to even guess what might be going wrong for you.
I use the MS Store version. The installer itself sits on the C drive, but I have the sim itself on my D drive. Every patch, just like todays, I first go to the MS Store and download, and install the update from there. When completed. I then launch the sim, which then tells me further updates are needed. It shows the correct location of my install, does not attempt to install it on a different disk, it does not lost my install, and force a re-install all over again (I suspect 99% of these are Steam users who just verified their install!!), and it proceeds to download the update. If I’m working from home then this has take a little longer in the past as everyone is trying to get it at the same time, but I am actually at work today, so by the time I get home, if it’s been released by then, it’s probably a 10 minute install.