When viewing the XBVR library from the Heresphere player, some covers don't show up if they contain certain bad URL characters (eg. ' ', '(', '[' need to be encoded as '%20', '%28', '%5B'). I can make those changes in the XBVR database, which fixes the issue, but it would be nice if HereSphere detected and encoded those characters automatically. It also does not want to display covers that were uploaded. Those are stored as a data URI.
On a side note, when a cover fails to load, hovering over the tile does not play the preview. The cover_url has to be fixed to be able to see the preview. It would be nice if it could play previews even when the cover image does not load.