Which ESP build version are you using ?
I could not workout how to find the build version. BUT when I opened Board Manager, in the ESP8266 section there was an install button active. I assumed that this meant there was an update to be had so I clicked it and the update installed.
All is now working as expected.
I would not have known that there was a new ESP Build avaiable. It would be nice if the Arduino IDE gave a message when such updates were available!
Thanks so much for taking the time to look at this.
Regards
BillP