Scoring estimator not working on Safari iOS

I’ve noticed that I am unable to use the score estimator on one of my phones (yes, I sometimes play go on my work phone).
It’s an iPhone 6S running iOS 11.2.5 (I think).
I just now realized that the same thing happens when the games go to scoring.
I had to go find my other phone just to be able to accept the scoring.

Forgot to add that I’m using safari ios.

Is this a know bug?