Dear Ann,
it might be the case that 5.9.1 is missing these two commits:
http://cvs.openacs.org/changelog/OpenACS?cs=MAIN%3Aantoniop%3A20180108095458
http://cvs.openacs.org/changelog/OpenACS?cs=MAIN%3Aantoniop%3A20180108095756
Once applied, the file-storage on dotlrn should behave as expected.
I will try to backport these changes to the 5-9 branch so that new tarballs won't contain this bug, then will get in contact with Arch package maintainer to see if a version update is possible.
All the best