The lack of icon is because Maintenance doesn’t include a TopRowIcon.png, which is what BeigeList (the bit that handles BLShowInFirstRow) shows as the icon. I’ve just added a TopRowIcon.png to CouchSurfer (just duplicated the AppIcon.png actually), and added the key to the plist, and it’s in the top row with its traditional icon.
I haven’t got Plex installed, but if BLShowInFirstRow works, then this will give it back an icon.