It may sound ridiculous, but on our Ultimo4K we experienced the same kind of problem with the standard image from VU+.
The reason for the small EPG was simply the full file system /media/hdd due too many movies saved. It's the same file system where the epg.dat file lives.
So please check whether there is enough space for the EPG file on the file system.
E.
Edit: @spevs Unfortunately I wasn't fast enough, so I didn't notice that you provided the log file in the meantime - where I can't find any hint that a full file system is the cause for the problem.