[Marcel Walter]

Hi Pat,
i just created an account here to reply to you. Maybe I can help a little bit.
I have the same issue and i do not know how to fix it, but a i know how to deal with it. If the problems occurs, try to hover over the top right end-point of the curve, maybe touch it shortly.
If i do this the mouse icon changes (on hover) and after that i can adjust all the other points again.
I really hope this helps you!

Marcel