Yes.
One of the corrections in the new Version 1.2.3.2914:
"(Metadata) Issues obtaining preview images from fanart.tv. (#5524) "
But nothing has changed. Still the same error. Unfortunately. 
In com.plexapp.agents.plexmusic.log:
_2016-10-25 20:50:59,388 (74059460) : DEBUG (networking:166) - Requesting ‘http://assets.fanart.tv/fanart/music/88679ca2-2080-4cea-8669-41ab4b8d865d/artistbackground/mena-maria-5371164e0fb50.jpg/**preview.jpg**’
2016-10-25 20:50:59,974 (74059460) : ERROR (networking:219) - Error opening URL ‘http://assets.fanart.tv/fanart/music/88679ca2-2080-4cea-8669-41ab4b8d865d/artistbackground/mena-maria-5371164e0fb50.jpg/**preview.jpg’**
2016-10-25 20:50:59,975 (74059460) : INFO (init:163) - Couldn’t add art (http://assets.fanart.tv/fanart/music/88679ca2-2080-4cea-8669-41ab4b8d865d/artistbackground/mena-maria-5371164e0fb50.jpg): HTTP Error 404: Not Found
_
PS: I have restart the Plex Media Server and do the “plex dance” before.
Results:
A lot of pictures for front:
But nothing for background:
