I've encountered what I believe to be a bug.
I covered my base with paintings, using up a LOT of fiber, and then when the artist was sufficiently trained, I went to deconstruct them all to rebuild them.
The paintings were deconstructed, and *appeared* to drop the fiber back (graphically).
But when I went to make more paintings, the fibers didn't count as available and disappeared as soon as the dupes tried to move them into storage.
Create several paintings, deconstruct them.