The workaround unfortunatly is to Wipe your device and then relogin to BBM. However. I would recommend you join the beta program and use BBM Beta versions. This will replace your current BBM with the beta version and may solve your problem.
If you do decide to try the workaround mentioned in the link I recomend using BlackBerry link to do a Partial Backup (Backup your App Data and Settings and media into three different backups. Only restore your app data and not your settings or media. IF it doesn't resolve your problem then restore you settings and media.
WARNING: YOULL LOOSE INFORMATION ON YOUR BB like texts and emails. so if they arent in the cloud somewhere then poof they are gone.