XF 1.2 After vb3 import, Find all threads by username not working


Active member
I'm trying out XenForo 1.2 RC1.
After importing my data from vbulletin 3.8, my users' existing posts don't seem to be attached to them.

When I visit a user's profile page and click "Postings", I get
"This member does not have any recent content."

The user's Messages count is correct.

Clicking "Find all threads by username" also returns nothing.

I just rebuilt the User Caches to no avail.
Where should I look?