Anyone else experiencing in the last 24 hours the top navigation of a site collection [SC] (well 2 site collections for us) disappearing. Both [SC] were provisioned a few years ago, but both have modern pages as their home page (all subsites do as well). On and off the top navigation (which is configured using Structured NAV) disappears from parent and child sites; then suddenly reappears. Could this, maybe, to do with the new mega menu slowly being released?? Any help would be appreciated from this wonderful community