Hey Tig. It looks like that download of UMP1 is missing a patch-pk3 that was later released to fix some errors.
The pk3 is ump_media.pk3. You can find it in various spots as ump_patch1.zip, e.g. http://games.mirrors.tds.net/pub/planetquake3/maps/ctf/ump_patch1.zip
Or this version of the whole ump1.zip download has it included: http://eclecticmenagerie.com/downloads/q3maps/jlctf2/ump1.zip
Thanks Johnny Law! The download has been corrected.
BTW thanks for continuing to post these updates; I usually don't have a comment but I always check them out.