Thanks for the info.
As mentioned above, this might have something to do with the new ROM you flashed to.
Note that we are about to release a major new version to Viber quite soon. When it's available, please try it out and see if your problem persists.
If it does, we would appreciate if you could take a minute and report the details to our support team using this direct link: http://helpme.viber.com/index.php?/T.../RenderForm/13
(when you submit the ticket, please make sure to specify the link to this page in the appropriate place in the form, for monitoring purposes). With this information, our development team will hopefully be able to find the source of the problem, and ultimately resolve it.
Thanks in advance
An official representative of Viber Media (Viber app.)