This is on a new iPhone 16, but I did transfer settings & data from a phone running iOS 15.

I generated my own CA, and it does not work under iOS 18. It works fine under iOS 16 on another device. There's clearly a profound defect in iOS 18 in this area.

"having a custom CA that issues certificates for internal servers is a well-trodden path that’s exercised a lot." Apparently not by Apple QA, then, because that's my setup and it doesn't work on my iOS 18 device. It works under iOS 16.

Hm, I don't understand that second response to the exact same quote!

Apple has acknowledged this as a bug. Fortunately, there is a workaround: Go to the scheme, say Edit Scheme. Go to Run (Debug) and find the checkbox for View Debugging and deactivate it. But please file a Feedback on this. In it, you can refer to my report: FB15492822

NP, thanks for the follow-up. But now the question remains (and lots and lots of people have this question): If we can't use NavigationPath, how are we supposed to pop back to the NavigationStack's root view programmatically?

"Have you checked what links are being downloaded in the Sysdiagnose files on the device?" How do you do that? I did a sysdiagnose and only got one big file. It did not appear to contain any relevant text.

Thanks for taking the time to provide that extensive explanation!