Wait, didn't I put a repeat there? Oh maybe I just forgot. OK here it is. (put one in.) come back there. I'm SURE I put a repeat there. Do it again. Chalk it up to me going crazy. OK I am not going crazy. I just dragged a double bar into a bar to mark the end of a section. I clicked on the default rest in the next bar with the intention of hitting N and adding some new notes. POOF my double bar vanished. This has been happening quite frequently. I'm on MacOS the version right before Catalina (resisting that for now) and the latest and greatest MuseScore. Anyone else seeing this? I eventually get them to stay there, it's something about what you do AFTER but I haven't worked out systematically what it is yet.