Hi Daniel, 

if you set any user security permissions in ubooquity , be sure to set the comic/book path settings without any symlinks -

for example : 

wrong  -  /share/download (it's a symlink generatet by qnap itself)

correct:   /share/CACHEDEV_01/download (this is the "absolute" path on my system, your's may differ, and the above path is the symlink target)

I'vo got the same "problem/bug" on my TS453mini as you, but after changing the path settings to absolute paths & 

rescan the entire database (incl deleting the "old/wrong" informations before the new scan!) all works fine  ..

in my humble opinion the java runtime cannot use or do his job false on symlinks, but using absolute paths is basically safer..

best regards from munich !

TierparkToni