Bluetooth Keyboard + Facebook Messenger loses focus constantly

With a Galaxy Note 8, Android version 8, latest of Facebook Messenger. I am trying to use my Keyboard K780 in Messenger and the focus is lost constantly after typing one letter. The only way I got it working is by putting focus in the textbox on Android, switch to another computer (F1), switch back to Android (F2) then the focus stays in the box. Not quite the best experience to start typing on Android. Any clues? settings?