Almost out of memory error

Getting an error "You are almost out of storage space! Minecraft has restricted access to this feature until you clear up additional storage space" in Bedrock when I try to load my world (the world itself is only 12.8MB)

Yet my Xbox has over 900MB free on the HDD

I have cleared the cache in the game (under settings, storage) - there was only 0.78MB in the cache items. Other items in the storage  - World items total 182.3MB, Resource items 95.6MB

Any ideas?