Unable to determine location

Today I noticed Location Services stopped working on my Mac Pro. I go to the Maps app, Google maps in Safari, time zone in settings, etc. and all report that location cannot be determined.

I fully understand that Location Services uses my Wifi router as one factor to determine my location. I have two different Wifi routers and can use an iPhone as a hotspot, and even after trying all three, there is still no location determination.

However, my iPhone can connect to the same Wifi and Location Services is working just fine there.

Any ideas? Thanks.