Good morning, we’re having this same issue. We have all the options under Advanced Settings enabled. When we test checkout it allows checkout if the phone field is blank and does not show the customized Placeholder for Phone to say that it is required.
We were having this issue with Safari as well using a contact form for a client site, but we found a plugin called “Contact Form 7 Redirection” and it works really well for all browsers that we tested on. I recommend it personally, as all scripting/queries were failing for some cases but this plug in fixed it.
