Littletad Submenu

Hello,
I have the sub menu which has not appeared for some time, I have the small arrows which indicate the sub menu but nothing to do.
I don't understand, it worked very well so far. I have deactivated the plugins which could come into conflict but that does not change anything.
And from time to time, the submenus work but I don't understand why.
I reversed menu extra and the main one but that doesn't change the problem

site : https://www.kids.numerimix.fr/

Help !

Regards,

I am currently testing with max megamenu to see if I can resolve my problem. But if you have an idea on the matter, it will be better. thank you !!