Thanks. Strange. I have used that component before and it works as designed--all closed on load. When I use it in a new RSD, it works. When I add it to another RSD (not my main one) on a current or Blank page, it works.
But, when I add it to any page--including new one--to my production RSD, it looks okay BELOW 291 in development screen, but not any higher breakpoint in development or Preview On. Looking at generated source code in browser, shows same code for working and non-working versions.
Production RSD has many pages. Must be something in one of them causing the problem.
Live in a steady joy!