Possibly related minor issue.
Server/client MC20.050 setup. I have a thumbnail style categories view by series, then composer, then album. Al files are audio.
On the server, the thumbnails are square (as are the original images). On the client, the thumbnails are rectangular (DVD-box aspect ratio). The images themselves are correct, but extended to the DVD cover art aspect ratio. BTW, the size extension is tastefully done by using a dominant color of the original square image, quite pretty.
No clue as to why the client and server look different, but someone somewhere is going to a significant effort to change the thumbnail aspect ratio...
This happens only for series thumbnails as far as I can tell, not for album/track thumbnails. It may be a leftover from when series was intended as a video field (hence the DVD-style thumbnails), but it's now defined for all media. In my application, I use it for CD boxsets.