[iOS] Drawing lines sometimes not working

Sometimes lines aren't captured even if you have drawn them for sure.

E.g. since I just started using Ringoton one of the new characters is 才.

The third stroke is never being accepted, the thin black line only goes from the bottom left to about 1/5 of the total length of the stroke. I've tried this about five times, always with the same result.

I've had occasional problems with detection of the drawn line on other characters too, but not like this.