I think this describes my issue, too. On two different Android devices, I can no longer seem to download cover images during a database update from my online account to my devices. This is a relatively recent issue, as I had no problems until about a month ago.
It'll check everything, then update the profiles, but then gets stuck on "update images" for hours and hours with no progress. I let it run for nearly three hours last weekend, and it didn't even reach halfway on the progress bar.