I had been having some trouble with Apple Maps and also with Waze in recent weeks. First Apple Maps failed, with the error “A Server with the specified hostname could not be found” but Waze continued to work. Then yesterday, Waze also stopped working with an “unknown error” message.
Apple Support helped me to troubleshoot this today. It turned out that the new firewall that comes with the latest version of 1Blocker was blocking first Apple Maps and then Waze. Once I turned off their firewall, both GPS applications started to work again.
I have sent a message to the 1Blocker support email suggesting that they tune their firewall.
Sharing this info in case someone else runs across this problem.