Now I've started filling it up, I've found when deleting anything from my home folders, I get the warning "Cannot move file to the Rubbish Bin, do you want to delete it immediately?". I get this whether I delete it from the /home folder, or straight from the /mnt/homedata folder.
I searched on Google and found this page which suggests checking the ownership and permissions of /.local/share/Trash, but I can't find this folder (and yes I've turned "show hidden files" on


