I just went back to grbl 0.9 and CM3 via this excellent set if instructions from Will:
There’s a few threads on how to go back to CM3 and grbl 0.9, but the above is by far the most succinct and understandable.
And… It fixed it. Now before I blame CM4, I’ll say that the first time I tried it with CM3, I swear it looked like is was back to the same incorrect spot. But then after switch laptops back and forth (I started this upgrade just because of getting a new laptop), somehow the error suddenly went away. I swear I have a talent for getting computers to give different outputs though receiving the same inputs. Most likely, I just did something different and didn’t realize it.
In short, thanks for all your help, problem solved. And if anyone needs to switch from CM4 back to CM3, use Will’s post above. There’s a few threads out there where the instructions are discussed, but the above one is the most understandable. thanks