I think we're dealing with the thumbnail browser:
..."album artist" panel ...
In this case, right-click where it says "Album Artist" and look for "show artist pictures" which will probably be at the bottom of the context menu. Uncheck that option, and you should see album art instead of artist pics.
If you find these instructions don't fit the view you're asking about, please post a screenshot of your full MB window so we can see which view you're asking about.
Home Desk ~ MB 3.3 Portable • Questyle CMA400i (ASIO) • Sennheiser HD 660S (balanced) / Audeze EL-8 Closed Back / Fostex TR-X00 Ebony • Teac AI-101DA • Jamo C93 + Dayton Audio SUB-1000
Work Desk ~ MB 3.3 Portable / Tidal • SMSL SU-8 v2 • Nobsound NS-05P • THX AAA 789 • Sennheiser HD 58X (balanced)
OTG ~ FiiO M11 • Audiofly AF180 / B&O H6