With the GC2 I would also question the flash life at it's end.

I had a flash that was near end of life and was getting a lot more missed shots than normal. Once it missed 3 or more in a row I changed out the flash and all is good again. This seemed to happen more the last month of its life. Putting is never an issue with putts, for me, being read and I like putting with the GC2.

Reading the greens is a skill that does take time to do well and it will come with time.