it looks strange, as I understand it worked well before upgrade. So it looks like some settings issue.
Try to connect to your NanoVNA with terminal, for example PuTTY. type "help" it should show you list of all supported commands, in such way you can check that terminal connection is established successful. Then execute this command:
clearconfig
It will clean all settings to default state. After that power off and power on device and check if your issue is fixed or not?
