Animation comp

Hi,
Making some simple curves with the animation CHOP. Not easy to replicate but in the last hour this has happened 3 times.
Simple curve in eg ty . - add a point , plug in a value of say ,4 and value goes essentially to infinity, and I cannot delete or ‘h’ to get to the point.

TD Build Pro 64 bit 2018 .26750

Win 10 Pro
Desktop i7-8700
RAM 16GB
GTX 1080-TI

Really having trouble replicating this. If you have any addition info or figure out a way to easily reproduce it, let us know.