I just installed Menu-block 7.2.3 on my Drupal 7.12 and on the main domain http://wsen.org everything looks fine. Since I run Domain Access to handle specific settings for the sub domain http://2012.wsen.org I have the option to enable that specific menu-block for both, one or none domains. First I configured the menu-block for the main domain successfully, then checked the box to activate it also on the sub domain. Sadly, it doesn't show up there at all (even when I enable the primary links so that it should definitively show up).
Besides the general Domain Access I use Domain Blocks to configure the domain-wide visibility of blocks and that worked well so far.
Any idea if it's your module that is responsible for this behavior?
Thanks a lot