Problem with Facebook Messenger - Suddenly old interface

Hi guys

Trying this forum for help... and hoping for the best ;)

All of a sudden when starting the facebook messenger app I get the old interface without the "bubbles" design.
The app also seem to use much longer time to refresh threads than it used to.

Attaching a screenshot. Note that the old menu's are back on top of the screen and the "new message" bubble is missing.

Installed version of the app is reported as: v. 2.5

Unit: iPhone 5
iOS 6.1.4

Also, I've tried to change language to english, complete reset/restore of phone from iCloud backup. I excluded the facebook messenger app from the backup and installed it manually after restore.
Hard reset of the device and uninstall/reinstall of the app also tested.

So... even if this is not a huge problem it's still anoying especially since noone seems to be able to resolve it ;)

Anyone have any ideas or experience on this issue?

Thank you

Regards