Safari displays a blank chat window

I have been noticing a few odd behaviors with Safari (26.5.2) occasionally and the most recent one is with a blank Chat window. I copied the URL and pasted it into Chrome to compare and there was no issue in Chrome (as seems to be the case with similar issues I've had with Safari). I checked the Pop-Up settings in Safari and it was set to Allow. Can anyone tell me if it is possible to correct this issue and, if so, how?

TIA

First screenshot is Safari and the second is Chrome . . .