SendInvites doesn't work for one friend, and she's not in GetInvitableUsers

Hey all, I'm making a little VR cribbage game for my family (Quest 3/3S, Godot with the Godot Meta Toolkit 1.0.3, testing on the ALPHA channel). I've got direct invites hooked up with GroupPresence.SendInvites, but they don't work for the one friend I've been able to test with.

Here's what I'm seeing:
- She shows up in GetLoggedInUserFriends, with the same user ID her headset gets from GetLoggedInUser.
- She does NOT show up in GetInvitableUsers. My other two followers do. From the docs I thought both lists came from bidirectional followers, so I expected her to be on both.
- SendInvites with her ID comes back with no error and one invite with her as the recipient, but it isn't active, the lobby session ID is empty and there's no destination. Nothing ever shows up on her headset.
- It's the same whether her headset is on or off, and the same the other way around when she invites me.
- If I open the invite panel with her as a suggested user, that invite does get to her.

What I already have set up: GroupPresence.Set goes through before the invite (destination, lobby and match session IDs, joinable true), the Data Use Checkup is approved for User ID, User Profile, Friends, Invites and Deep Linking, we follow each other, she has the app as an ALPHA tester, and her privacy settings are open.

I found a couple of older threads that sound like the same thing but never got an answer:
https://communityforums.atmeta.com/discussions/dev-unity/quick-invites-not-sending/1135637
https://communityforums.atmeta.com/discussions/dev-unity/anyone-get-quick-invites-to-work-on-oculus-quest/959178

So I'm wondering:
1. What decides who ends up in GetInvitableUsers, besides followers and people you've recently met?
2. Why would SendInvites make an inactive invite instead of returning an error?
3. Am I only supposed to call SendInvites for people who are already on the invitable list?

Thanks for anything anyone has!