SwiftKey flicker/lag

Since a few updates SwiftKey started to flicker, i.e. when I pick the text input area in an app (doesn't matter which one, same behaviour all across the board) SwiftKey shows up, quickly vanishes and then shows up again. If I start typing before it vanishes nothing happens until it reappears. That's annoying, but I can stand it if it weren't for..

Sometimes SwiftKey doesn't reappear, but the standard iOS keyboard. So I have to manually switch keyboard again.

Quite annoying, frankly. A fix, please?