if you’re talking about https://forum.inaturalist.org/t/project-drop-down-menu-list-inquiry/10778, i think this is unrelated to what you’re describing.
what you’re talking about sounds more like https://forum.inaturalist.org/t/recent-projects-list-in-header-does-not-show-recently-created-projects/3427, and this thread probably should be merged into that bug report.