Single line staff is spaced as if five lines
If a part is on a one-line staff, you would expect things that are spaced to be above the top or below the bottom of the staff to adjust to those two places being on the same line. But MuseScore treats it as if there are four more invisible lines below a visible top one. This looks slightly strange in a score with the apparent extra space below the one staff among many, but it becomes a real problem in the part itself:
Is it too late?
EDIT: That one mezzopiano at the top that's looks like it's in the right place is because I manually moved to the right place. Just so you know.