This is interesting: In Snac, I can see a Threads post boosted via a Mastodon account. It's a post from a few days ago on the account I tried to follow earlier. And according to the timeline and API, I am following them from Snac. But they aren't showing up on the list of people I follow.

This suggests that Snac is able to interact with Threads posts, and is able to follow Threads accounts, but runs into trouble retrieving Threads profiles.

Partial federation is a more interesting problem IMO than no federation, so now I really want to take a look at the logs!