Can't respond to text messages

[Icarus3000]

I've been using Fongo mobile android version for months and months with no issues.

Suddenly today, I can not respond to text messages. Clicking the "send" button doesn't do anything.

I can still create new text messsages, and as a work-around I can create a "new" message to a contact, and type the message and click send, but this is rather annoying... Is this a known bug? Would deleting and re-installing the app fix this? I've already shut down and re-started my phone, but this didn't help.