Can't get iOS Push Notifications Working

I've followed all the instructions (as far as I can tell) and I've looked at other community posts, I still can't get it working.

Some clues in case it's helpful:

1. I'm using Firebase Authentication and Firestore.

2. I've double checked my keys and identifiers and I think I've configured things correctly.

3. When I push "Send Notification" on the testing page, I've made sure that I'm on the iOS home screen on my physical device (connected via a cable) and that my app isn't in the foreground.

4. The "ff_push_notifications" collection appears in Firestore and gets a new entry each time I try to test from the manual sending screen in FF.

5. At one point, I was having an issue where the Deploy button on the notifications settings page was giving me an error and telling me to contact support. However, after I disabled and reenabled notifications a few times, the error went away and the green checkmark returned.

6. I have "Allow Scheduling" disabled. (Though I may have toggled it on/off in the process of trying to figure out why things weren't working.)

7. Only once have I gotten the Notifications Permissions pop-up on my physical device (iPhone 15 / iOS 18.1.1). When I said "Yes" to the prompt, I still couldn't receive notifications.

8. I went into Google Authentication to delete the app account I was signing in with and then recreated it from the Sign Up page in my app, in the hopes that this would trigger the Notifications Permission pop-up again, but it hasn't. I've tried signing in with several test accounts and none of them get the permissions dialog. (I also tried disabling and reenabling the Permissions toggle in FF, but that didn't seem to help either.)