Menu manager - dropdown list disappears as you mouse over it

[Nihonto]

I am using menu manager to do a dropdown list of external links.
Once I build the menu, whenever I click the parent, and the menu drops down...as soon as I move my mouse over the dropdown list, it closes the dropdown. I need to go up again, click the parent....drop down...move mouse and the whole thing collapses again. Positioning the mouse doesn't help.
It does this 5 or 6 or 8 times until suddenly it seems to think it has loaded everything ok and then I can navigate the menu fine. Takes about 30 second of 'whack a mole menu' before all is fine to select.
Hard to explain to my members they need to repeatedly do it until it works.
Anyone have any ideas? Could it be browser related? Using Firefox. Board is at https://www.militaria.co.za/nmb
Nihonto links dropdown.

[opentype]

Yeah, it’s a known issue in 4.4. Here is previous discussions with tips how to resolve it: 

 

[Nihonto]

Thanks! Will go through the article.