Octatrack CF zero space available while copying from macos finder

FYI
This was a bit problematic:
Tried to copy a sample after chopping it up and quantizing the slices in Reason. I’ve exported the file as an 44.1kHZ 16-bit .aif sample. Copied in finder and head over to the octatrack’s mounted folder. Paste. Not happening!
“Zero space available.” After fixing the CF card with “Disk Utility”, the problem persisted. A couple of minutes later, I’ve noticed that the file was on the Desktop in macos, and I use iCloud syncing for Desktop + Documents. So, i guess the file wasn’t a real file, but some kind of a resource fork (is this the term? correct me if I’m wrong).
I then copied the file into a folder (for example ~/Downloads) which isn’t iCloud-synced and the file became “real” and copyable to the OT’s CF card. Boom, problem solved. Have you guys encounter similar things?