Believe this issue will be the same for various non-latin input methods. Not sure how to begin tracking it down, but if you have a clue, please tune in. Worth mentioning is that the issue is the same across all browsers i've tried on android, including chrome, so probably its a incompatibility issue with the IME.
I've been using
And below to verify that its not limited to numerical input
Can also verify that the default japanese keyboard has the same faulty behaviour.
One hint: if you backspace out the mask pattern until the cursor is at the beginning of the input and type something you will be able to input one character. This can be done again and again.
I've merged #245 which seems to fix some android issues.