Disappearing barlines (sorted now)

I don’t know how I did this, but all the barlines have disappeared in Galley view from the various instruments in my Percussion player - except for the Glockenspiel and Bell Tree, for some reason. I thought it followed my decision to change the timpani instrument for one without key signatures, but the barlines are still absent after experimentally changing it back.

How might this have happened, and how do I get my barlines back?
UPDATE Well, what do you know. I closed and reopened the project, and the barlines were back! I haven’t deleted the post just in case the details might be of use somehow.