Thanks, @mmustac, but after removing contents of that directory/folder, half my chosen menus didn't reappear (like I have no 'copy/move to,' and have compress but not extract, no install, no download with Kget, and can service-menu-open/-play/-edit some files/media but not others I used to)... with the amount that disappeared, I don't think it's just a KDE5 dolphin bug itself rather than something got corrupted. I use dolphin on Slackware GNU/Linux, FreeBSD Unix, and had even installed KDE software in Windows for users and might do so again someday if there's really a reason to use that (probably isn't a reason)... maybe that category--operating system (OS)--is another good one for add-ons, as I see may apply to some, or some at least assume certain software that's on certain OS. Some also say don't install it, just download and run a .sh. Lots of great stuff in the KDE store but for now I ended up not using much of it except in themes...