[2021] Despawning mining rocks?

I mined out 300-400 iron ore blocks earlier today, planning on leaving them to log on now to pick them all up 20 at a time and drop them in my stockpile. However I have logged back in and my entire mine is empty, all the pieces of iron ore I mined out of the walls waiting to be gone have disappeared to the very last piece.

So my question is, do blocks like these that are not collected disappear/despawn? As I have control of all tiles in the mine and no other players are authorised.