Unable to accept legacy contact offer

A family member sent me an iMessage trying to add me as a legacy contact. When I click the link, however, it takes me to an Apple support page telling me about legacy contacts. To further test this, I had my girlfriend send me a legacy contact request and I sent one to her. The one she sent me worked fine - rather than take me to the Apple support page, my System Settings app popped up and I successfully added her. The one I sent to my girlfriend, however, acted the same as the one my brother sent me - it just brought up the support page.

If I copy/paste the various invites into a text file to look at the URLs, they are all the same aside from the GUID:

https://setup.icloud.com/private/trustedcontact?flow=digitalLegacy&id= <variable GUID>.

So for some reason some of those GUIDs are not being recognized while another is. All devices involved have been updated to the latest versions and I have tried both with my MacBook Pro (it's brand new - 2 months old), my SE iPhone, and my iPad(slightly outdated but iPadOS version still supported by this feature). I tried calling support but, though they were as nice as could be, were unable to help.

Anyone have ideas?