Embedded Scripts do not show in Safari

[Stephen Hind]

Has there been a recent change in Apps Script or Safari?  Embedded Google Apps Script in an iframe (on WordPress, for instance) no longer displays in either iOS or macOS Safari, not even an error, just a completely blank area.  The scripts do display  in a Google Sites without issue.

The JavaScript Console shows that the iframe is trying to display the Google sign-in page despite already being signed in in a different tab.

Has anyone else noticed this as a change has it always been this way and I've never just noticed.