This was first experienced for me on my BlackBerry Torch 9800 with OS6 and the source of the problem is a conflict between Google Sync and BBM. The quickfix is to uninstall BBM and then reset your calendar sync and then reinstall BBM.
Here are the steps in detail:
- Backup your BBM contacts etc. and then remove BBM. In OS6 go to Options --> Device --> Application Management --> BlackBerry Messenger --> Delete
- Note: some users experienced difficulties deleting BlackBerry Messenger; in such cases first try to install the latest version available from the BlackBerry App World and then delete it from there; for some reason the default "core" installation bundled with the OS isn't removable.
- Consult http://brattex.blogspot.com/2011/05/blackops-that-google-calendar-syncing.html for initial steps and for methods to backup your calendar. You can skip the steps on deleting service books (i.e. do not do steps 3 and 5) but follow the rest.
- After you've run Google Sync and verified that it's all in your default calendar ... reinstall BBM.
I would be really interested to know if this solution worked for you so please feel free to leave a comment below or give this a thumbs up, +1, like, etc.