I am in the process of assembling my new bike. I'm installing the headset and I have a noticeable gap between the top of the headtube and the bottom of the dust cover.
The bearing is seated in the frame correctly, the expansion ring is on top of the bearing correctly but there is about a 2-3mm gap, you can see the silver of the bearing. There is a rubber skirt inside the cover, I removed it and tried it but was no different.
The pic below looks like the cover is on a bit of an angle but it’s just the photo, it is straight.
Is there a solution to this? The headset and bearings and other pieces all came with it so they should be correct.

I suspect the bearing seat (inside the headtube) isn't as deep as the headset manufacturer designed for. But I see no reason that the headset won't work. At worst the upper stack might see a bit more grime getting in but that's more about periodic maintenance as grit gets into nearly any gap given enough time and exposure. BTW the lower stack is more the concern as it sits in the direct line of fire of any water spinning off the tire. Andy

It will work just fine as it is with the gap, it is just one of those things that will annoy me each time I look at it. The lower bearing sits perfectly.

I suspect that gap will close somewhat when the stem and spacers are installed and the top cap is tightened enough to set the preload on the bearings

Just make sure your expectation is what the manufacturer of that was thinking when they designed it.

I tried a cone spacer/cover that I had lying around and the gap is much less but still there. I’m think I’ll just use that one instead.