For the past year I've been building a long railway. I've built it through 3 max zoomed out maps so far. Most of the time I'm far from my base building the railway.

Recently I noticed that in my base my house is gone. It looks like this part was regenerated, there are only a fence and wolfs that were in front of the house. The rest of my base is still there.

Along the railway between my base and the first railway turn, huge holes in the ground appeared. They have no bottom, it looks like there's a sky on the other end. Also some other things along this side of the railway disappeared, mainly were replaced with other blocks.

I'm not sure when this happened. On Sept 26 I commented here under another issue that my minecart with a chest disappeared. At that time I didn't go back to my base, I just kept on building the railway. But I have copies of my world from the same day, some time before the minecart disappeared and right after. In the "before copy" the world is ok, in the "after copy" everything is broken. So those 2 events probably are linked.

I haven't done anything differently, I saved like I always save. Is it because the world is so big and I've built such a big structure?

As I mentioned, from Sept 26 after the minecart was gone I kept building and exploring and mining, I've done a lot of progress. I'm making a lot of backups but I've been making them without knowing that half of my base was gone :/ So now I have to sacrifice almost a month of progress :/

Anyway, that broken world is not working properly, it lags a lot, which almost never happened before, and when I went to a new area there was a normal village (not zombie) without any villagers, cats, golem, nothing.

I enjoyed the games for over the year and this bug discouraged me completely.