Dropbox and Box can't write to my mini

I have used my Drobo mini for months now as the place I store my Dropbox and Box folders. About a month ago, the two apps started telling me that they can’t find the folders and can’t create new folders on the mini. None of my normal permissions-fixing apps work on the Drobo. Does anyone have this type of issue or suggested solutions?

hi bill,
can i check how many volumes (or drive letters) you have on your drobo, and also how much free space is the computer (and dashboard) showing as freely available there?

if there is space, what happens if you instead try to manually create (or paste) a copy of the same file maually via your computer (not drop/box), or something around the same size or slightly larger?