mobile menu is not working

If anyone reads this, maybe they can help me? https://www.neilangroup.com.au
On the desktop version the submenu under about works
On the mobile version, it isn’t showing.
I think it could be a transparent header issue but not sure?

@arte99 Can you share your URL so that it can be viewed?
Do you have an off canvas menu set?
Have a look here : https://wpastra.com/docs/toggle-button-for-desktop/ or https://wpastra.com/docs/create-mobile-header-with-header-builder/ for example!

@mlehmann Can you create your own topic please ??

I didn’t have an off canvas menu! So stupid of me ??
Thank you very much for your help!