KE8CPD6,
I had the same issue as you. After clearing the config data and recalibrate, it seems to work OK. Here is what I did.
- Plug in the USB
- Use putty or any terminal software to connect to NanoVNA
- At shell interface, type "clearconfig", then "saveconfig". This is equivalent to load "CLEAR_MEMORY_DFU.dfu".
- Redo calibration.
