[BUG} Custom Menus are not working

I have created over 20 menu links: https://cl.ly/2M1i3D3r2g1A0V441G3d
and 3 main menu groups: https://cl.ly/223D1d3x0Z1H142M3L1X

however when i try to save the menu it, instead of saving ,
it loads ALL the image from the site!
https://cl.ly/1p0O0r0u1U3X0u0B1U3W

* this did not happen before.
And nothing changed in the site. ie no new plugins installed.

p.s. these are my list of plugins : https://cl.ly/0m473L3d3e1N460O0X1I

I tired upgrading from 3.3 to the latest 3.4.1 vrsn, and it continues to happen.

please advise.