No news yet, I submitted all my logs to RIM Support and they state a 2 busines day turnaround after that - even post-escalation with Advantage support.

In addition to event logs, magt/calh/sync logs, they had me perform some test scenarios and documenting the event uid of calendar items (retrieved by opening a calendar item, holding ALT and typing "view".

I'm seeing those warnings on my test mailbox, which is what we're troubleshooting now. They persisted through a wipe/re-add. It may be mailbox corruption, too soon to say.