Menu not letting me add Sub Items

Hi!

I have been trying to add a Sub Item to the Menu, I quite simply do what I normally do which is adding a Page or Project to the menu, and click ‘under the’ – I tried to grab and move the page ‘under the’ but once I save it it just reverts back to the top level,

like in this screen grab

Any advice please? Thank you 🙂

Ops – must have been a glitch, it is sticking now 🙂