Max size for shared folders?

I have recently purchased a MyCloud Ex2 for backup of my files while I’ll be changing motherboard on my system. I have begun transferring my files to two different Shares, but this morning I couldn’t transfer any more. When I try to transfer, I get the message “That there is not enough space on …”, even though I have > 2 TB available according the Home screen.

Is there a hidden limitation somewhere or can I do something to transfer the remaining hundreds of GB?


Edit: I’ve been transferring smaller chunks, and it seems like there is plenty of room. I feel a bit stupid, as I was trying to transfer more than 2 TB and thought that the filesystem would merge before checking if there was enough space.