Double chests split into two and chest textures missing after going through a nether portal and back

I went through a nether portal, then I immediately went back to the overworld (which took around ~10-15 seconds) and I went back to my base and my double chests were split into two, and the textures of a couple of them were missing. This was on a realm as well, I don't know if that has anything to do with it.