How is my home not considered a familiar location?

Did you set your home location in these settings?

Settings > Privacy & Security > Location Services > System Services > Significant Locations

If not, that's almost certainly why. I don't think it will just register a location as "familiar" by itself. As to why a text didn't arrive, that's something I can't answer. You'll have to resubmit and wait again, I'm sorry to say.

Regards.

Adding your Home address to Maps will help, but unfortunately not immediately. That would be too easy for a bad actor to quickly bypass the security delay. The message you get will expire after a short time and that is why it started over again in the morning. When I did it, there was just a pop up on the screen after the hour, I don't believe it was an actual Text Message, but I may be wrong.

After the hour, you will be able to turn it off and all will be back to normal.

My apologies. I obtained that information from another Community thread and parroted it without verifying, something I should never do. That section will show what your device has learned, but there's no way to manually set a Significant Location there. Whether adding your home address to Maps, if you haven't done so already:

Add or change your home address in Maps on your iPhone or iPad - Apple Support

would make any difference I don't know. This issue does appear to be one that other people have encountered, with no definitive solution I can find. Absent any other suggestions from other users here, this may require changes to the system by Apple. Whether such changes will be incorporated into the upcoming iOS 18 I don't know.

Again, sorry for the misinformation. Regards.

Apple may be being very conservative about what constitutes a "familiar location" in this circumstance so as to prevent a thief from being able to force an iPhone to adopt their own location as "familar" too quickly and easily. But I don't know; that's just a guess though it seems logical. As such, they're probably taking the approach of making it more difficult. But we'll see how things develop.

Regards.