Sealing maps and map drops

Does anyone know: if you sealed all maps below, say, T15 and you run a T15 map which will happened?

1. All drops that would drop a map end up being T15 or T16
2. Any map drop that would drop less than a T15 would "disappear" and there would be no drop

I imagine it's number 2, but I'm wondering if anyone has insight on the mechanics or has tested it.

This was debated a lot before Atlas and I think people tested it and said it drops as a T1 since you can't seal those (going off memory here).

You can seal T1. At any rate, I did earlier in the league.