Focus order issue when exiting drop-down menus, using keyboard-only access

Replication steps: Use the tab key to navigate a dropdown menu with only the keyboard. Example affected menus: Dashboard course overview block filter, sort and video menus; custom menus in top nav bar. Tab to reach menu. Click enter to open menu. Tab through menu items. Tab again to exit menu and move to next focus item (ie exit the menu).

Expected behavior: after tabbing to end of menu items, focus moves to next focusable element in the DOM.

Actual behavior: When tabbing out (menu closes), focus moves to the next focusable element for a split second, then bumps back to the previous menu. This is not expected behavior and may be confusing to users with mobility disabilities, users who are blind, and users with cognitive disabilities.

For example, tab order/behavior for the Dashboard Course Overview block sort menu:

1. Sorting Menu button (press enter to open menu)
2. Course name (menu item)
3. Last accessed (menu item) (tab again to exit menu...)
4. Summary menu (next focusable item)- focus only stays for a fraction of a second and then bumps back to
5. Sorting Menu button