Picture and Cover Art not changing on Google Chromecast Display

Core is Nucleus+, Music resides on a QNAP NAS, remotes are iPads and an iPhone, 5 Displays on TVs using Google Chromcast Dongles

About 20-30% of the time, when a song ends and another begins, the Artist picture does not change. It sometimes finally changes in the middle of the next song and sometimes not till the following song. Much less often, the cover art does not change. I have also seen several instances where the cover art changes to the correct art and in the middle of a song, it disappears and is replaced by a blank record album. This behavior occurs on multiple displays. Thank you.