Problems with Mac App Store and old software versions

I have a MacBook 6.1 and have two issues, the first one is that I can't use High Sierra because there is a bug that in the App Store you can't see the purchased items, but I am with Sierra because it works better for some reasons, the problem is that I try to download an old version of Xcode, and says that I require macOS 15, but it is in the list of purchased and should be downloadable, I want to ask if there are someone who has a similar problem like this and if there are any solution that I could do with the app store to make it work, thanks for all