Viber does not work properly

I have a Tab4 with Android 7.1 and Viber does not work properly on it. The app installs fine and activates using my phone and a QR code.

Calls can be made but the party on the other end cannot hear me, I can hear them fine. The speakerphone button of the app is greyed out and the mute button makes no difference.

I have tried resetting the tablet and installing Viber as the first app from the Play Store but the result is the same.

WiFi is the connection method and signal is very good.

Skype is an analogous app and works perfectly. App version is 7.9.4.11.

I also use Viber on a tab3 (android 6) a moto e4 (7) a Samsung phone (5) and a Nexus7 (5), all work fine.

I hope someone can help as this is a deal breaker for my wife.

Regards, George

Problem solved by new release of Viber App today, all good.