I mined down to a quite large cave system and set to work exploring it.
I usually put a wall covering explored areas that i have mined the ores out of so that i do not go down them again and get lost, however, in the cave system i have being doing quite recently i put the walls in place, took all the ores i mined back to my house and stayed around my house building things for about 5 minecraft days, i went back down to the cave to explore more of it and the walls i had created have disappeared. On top of this it seems more like the server loaded up a slightly older version of the exact same map i was on because when i cover an area in a cave with a wall i also take my torches that i used, since i wont be using that path anymore there is not a need to leave my torches there however this time i went back and not only had my walls disappeared but all the torches were back on the walls which really surprised me.

What should of happened:
The walls which i had created should of still been in place when i went back down into the cave

What actually happened:
The walls had disappeared and the torches i had removed from the areas had come back onto the walls.

Steps to reproduce:
1. Go into a cave
2. Explore quite alot of it
3. Block off the areas you have been that lead to a loop or a deadend
4. Take the ores you mined back to your house/shelter/base (Outside visual range of the entrance to the base)
5. Stay at your house/shelter/base for a number of minecraft days (5+)
6. Go back to the cave and go back down, the walls you put in place to block off the areas that lead to a loop or a deadend MAY have disappeared.

(I say may in there for the simple reason this is the first time it has happened to me and honestly i did not wanna run a risk of it happening again)

P.S. Sorry just remembered, when i went back down into the cave after the 5+ minecraft days back at my house i noticed that coal and iron and lapis all respawned in some locations i had previously mined.