we've seen the following behaviour at several sites:
Mobility builds 794 and 882 / GW802HP3

Basically everything's working fine with Apple devices. For the Galaxy devices (maybe for other droids as well, but the S2 are the only Droids used in these environments) problems arise once you create a multi-user appointment. As soon as you invite someone (internal or external doesn't matter) the appointment never makes it to a mailbox, neither to the creator's one nor to any other. This works fine for the same accounts with iphones, ipads, iwhatsoever with both 4.x.x and 5.x.x builds.
The affected Droids are running 2.3.3, 2.3.5 and 4.0.3, the only common denominator is that all these are Samsung builds. I've tested a friend's Galaxy S2 with an open 4.0.4 build (based on Google sources), this one does NOT show the problem and properly synchronizes everything in any direction.
Makes me thinks of a problem with the calendar app on the Samsung builds, but i couldn't find any references to similar problems.
Can anyone confirm the issue? Or can anyone confirm NOT to have the issue?