Could you first check if the files have tags at all? (and the file information is not stored in some kind of local database)
If they have: check the version: V1, V2 or APE? Try one after the other.
Also check: do you use ISO or UTF coding? Try the other setting.
UPDATE: You need to go into MY MUSIC/OPTIONS/PLAYER SETTINGS/SKIN/ALBUM ART and the pictures show up.
What I don't appreciate is that regardless of the size of the picture, the image doesn't fill the screen; it is a postage stamp at the top (and you don't seem to need to keep it under 100kbs as was the case on the LG RUMOUR TOUCH).
I wish there was some way to use my LG RT on another carrier, but I understand because they use CDMA technology, that is not possible.
Hope this helps others who might get this telephone.