Posted here for information, since the Curse comment section decided not to work today. This is not an issue with MBB per se, but merely the consequence of interaction between MBB and Leatrix.

If (like me) you use Leatrix Plus in addition to MBB, the last update added minimap specific options which cause MBB to no longer work.

Specifically:

• "Replace non-standard buttons", which replaces all buttons with standard LibDBIcon buttons (also removes SexyMap elements)
• "combine addon buttons", which does something similar to MBB but seems to interfere with MBB (as well as SexyMap)

These options can be found in Leatrix under "Interface" > "Enhancements" > "Enhance minimap". Disabling them fixes MBB.