Modern Greek speakers tend to squirm when addressed in the politeness plural, unless they are deliberately being high and mighty. The politeness plural connotes negative, not positive politeness to them, and emphasises social distance. Greeks don’t like social distance, they like being friendly and in your face. The exception these days would be officialdom and other explicit hierarchies, and even there, I’m stretched to think how much of that survives. I suspect it survives more in the Church.
As a diasporan, I approach new acquaintances in Greece online, using the politeness plural a fair bit. They will put up with it in the first exchange, and no longer. The explicit signal to cut it out, if you persist, is στον ενικό, είπαμε. “I told you: singular!”