WordPress Sub- Menus will not save

When in Appearance>Menu, I am unable to save any menu change that relates to sub menu’s.

I can create new menu items, but if i move a box to become a sub/child menu, and click save, it resets everything to the same level. This makes the main page of the website spill over and have links all over the homepage.

So far I have tried:

Turning off all plug-ins.
Removing parent status in page attributes and re-adding it.
Updating WP
Updating the Theme(Jupiter)
Changing the Theme
Deleting the menu and trying with a smaller menu(regular menu has 25 items)
Increasing the max vars limit(6000) and memory(256)

Have also noticed that the links don’t actually work anymore. None of the links on the old menu did anything, and on any of the smaller ones i am now creating, they do nothing when clicked on, even though i have them directly linked to specific pages.

I’m also noticing problems in other portions of the wbsite such as Events disappearing.

We are using CP Panel to host the website.

I have a maintenance window setup on the website, and will turn it off when i get a response.

https://www.operationcareinternational.org/

Any suggestions or experience with problems like this?