My iPhone does not show up in the Finder sidebar even when I have "Show this iPhone when on Wi-Fi" selected

My iPhone 12 does not show up in the Finder sidebar even though I have "Show this iPhone when on Wi-Fi" selected. In fact, the setting usually doesn't stay "saved" for more than a few hours.

The phone does show up when it is connected to my MacBook (2018) via USB cable but even though I check the Wi-Fi sync, it never works.

I have tried resetting Location and Privacy multiple times but it never makes a difference. I have also reset Network Settings but that didn't work either.

Clearly not the worst problem in the world but it is frustrating. It used to work (sporadically) when my iPhone was connected to my old 2012 MacBook Pro but I finally moved my Music library to the newer machine.