I’ve been on the 670G for 3 months as well and I also feel like when its working well its great…and it does have glitches…which I expect with new technology and with the safe guards in place I don’t mind some hassles for the new features and increased freedom it provides.
I have had the same problem as you cite and I have a direct Medtronic rep I deal with (who did the training with me) and she is more knowledgeable than the general support line at Medtronic, I’ve found. My rep told me to let the pump “cool down” for 30 minutes and do not enter the BGs or do a calibration for 30 minutes or exactly what you described will happen (and has happened to me). This comes from her direct experience working with 670G users newly on the pump.
If you want to share any info directly on your/my experience using the 670G, let me know. I’ve figured out a few things with regards to sensor placement, exercise, etc. that Medtronic doesn’t yet have an official guidance on.