Thanks. We're looking into the lost album art on upgrade at:
http://www.ventismedia.com/mantis/view.php?id=12682

As far as the fact that the lock screen player is gone in Android 5.x, there are some security changes in 5.x.
Go to Android Options > Sound & Notification > and Set When device is locked to 'Show all notification content' . You can also set App Notifications > MediaMonkey > Priority, and elect to hide notifications from any apps that you don't want to have appear on the lock screen.
We plan to make additional changes in this area so that you don't have to go through this process: http://www.ventismedia.com/mantis/view.php?id=12584

-Rusty

Same issue here. Upgraded from Android 4.4.4 to 5.0.1

Album art no longer shows. Lock screen player is gone and notification bar icon no longer appears.

Al,

What OS version did you upgrade from ?

-Rusty

using MMA version 1.1.0.0406 with Pro licence

After upgrading my phone to Android 5.1.0, none of the album art shows up in MM. It's still there on the phone, but none of it displays in the app.

Any thoughts?