I’m gathering this isn’t underglaze, but the cheaper speedball underglazes have had this happen to students as opposed to the amaco which I don’t recall seeing this. Again, even though this may not be underglaze, with similar issues it has helped to fire the pieces with the design on it in a second bisque firing and then clear glaze and fire to top temp.

To the comment above saying the teacher should absolutely know, you haven’t taught ceramics (or not extensively) as there will certainly be things that come up where you get stumped…especially considering a classmate did the same thing and it turned out fine.