Can’t add to Menu

I can’t add items to the built-in menu. I have been doing this for a while. I was a couple of version of WP behind but it still doesn’t work after upgrading. We did have server issues and locked some things down. We opened it up so I could test it and that didn’t fix it. It’s locked down again.

Could it be a menu limit?

Here’s the site. Trying to add to past productions. 2017 shows up if you click on Past Productions because it’s a child. But it won’t show up in the menu. Can’t delete a year either.