[akovia]

Ah, there is your problem. You have named the image wrong.

It is not disc.png, the filename must be discart.png so it matches the the advancedsettings.xml entry. From v18 most skins moved away from disc.png/cdart.png and are now using discart.png.

Change the artwork name and rescan the movie and it should work.

Your advancedsettings.xml file is loaded correctly. The only other error I can see is the following which (I think) is a permissions issue...

xml:
ERROR: Failed to close(export/Media/Movies/House of Flying Daggers (2004)/House of Flying Daggers (2004) 720p.nfo) - close call failed with "NFS: Commit failed with NFS3ERR_ACCES(-13)"

Thank you @Karellen 
I don't know how I missed that. I guess sometimes you just need other eyes. 
It makes sense now that this probably happened when I added everything to the advancedsettings.xml and removed artwork beef. I have been working on the TV side and didn't notice until I removed and re added the sources.

That access error has been driving me mad for a while now and went down the google rabbit hole trying to get to the bottom of it but never could. I have mass edited my entire NAS to 755 permissions for folders and 644 for files, but I still get those errors. 

Thanks again!