SSL/Secure status differs across browser?

Hi Circle! Weird situation here, would love some guidance.

My client heard from a site visitor that the site is showing "not secure" (didn't mention what browser). When I dig in I see the settings are good inside Squarespace - SSL is active, Secure/HSTS Secure. The domain was purchased through GoDaddy, and we followed the help steps to configure DNS. I set my client's site live Feb 19, so the dreaded 72 hours are well passed.

The site shows Secure on Chrome, Chrome Incognito, and Edge. It shows Not Secure on Chrome Mobile and Safari.

Any idea why this is happening, and how to resolve? Or is this better suited to a Support ticket than Circle Forum?

Thank you!

Commenting to say I have a similar issue. Everything seems fine on the SSL end, but some users are telling me they can't see my site due to security warnings. Desperately need help on this, if anyone with power here is watching.

Im having the same issue with several of my client websites. Would love some help as well.