Missing iCloud bookmark folders

A few weeks ago, for reasons unbeknown to me, my dozen or so iCloud bookmark folders with dozens of websites in each have disappeared. Each folder had a relevant name; Schools, Jobs, Banks, Gadgets, etc and within them the numerous individual websites. Now all I have is all those bookmarks individual listed under bookmarks in no order, does anyone know how I get them back into their folders? The actual named folders have disappeared. I have rang Apple many times, but they couldn’t help, but suggested I wait for the next iOS update in September.

This affects all devices; iPhone, iPad and iMac, and not just my iMac, as I was unable to select all devices.