Just measured the adapter with a caliper. It is roughly 22.2mm (with a non-digital caliper) all the way down. The steerer is also 22.2mm. The only thing I can figure is that maybe the wedge isn't engaging when the adapter is raised? Below is a pic. Not much room in the headtube for the clamp to engage since the top tube and bottom tube have an opening inside the headtube. See the pic below.

https://www.pedalroom.com/bike/1986-...eedfixie-32051

Dave