"Pop up not added"

I’m getting “pop up not added” on just one of my subsites.

I have a multisite install, all plugins up to date. 5 websites are using Pop up. I used “new blog templates” just as I had with the previous 5 and created a 6th. Did all of my changes, activated popup and when I go to add a pop up for the 6th site. No matter what I get “pop up not added”. I searched and saw someone else chmod the plugin files to 666 and it didn’t work for me.

I can add additional popovers to other sites in the multisite installation still without any issue. Any ideas?