Extra clef appears when importing

I see a clef indeed bt no key signature. Was that a typo? In any case, the clef actually seems to be correct, it's present in the file, but a bug in 2.3.2 prevented it from being displayed. You can see it in 2.3.2 if you delete the section break, though.

So, did you mean to say "clef" in the title? Or are you saying you actually see an issue involving key signatures?

In any case, as I said, I see the clef in the score, so it appears correct to me. It seems you added the clef change in 2.x because I can see in 2.3.2 it if I delete the section break. I suspect you meant to add it before the measure, not within the measure - or a bug in 2.x caused this to happen. But regardless of how the score got the way it is, it does appear that 3.0 is displaying it correctly and 2.3.2 is not, from what I can tell. If I delete the incorrect clef in 2.3.2 and resave, it displays as I think you expected. Or, if I add it correctly as a clef change before the measure rather than within, it also displays as you expected. So I think the lesson is, don't add clefs within measures unless you want them to actually appear that way.