Did I see you are running Woocommerce AND the Avada theme? If so this might be of help:

https://simple-press.com/support-forum/sp5-general-topics/cant-add-new-topics-issue-found-in-combination-with-woocommerce-plugin/#p158511

If not then I need to pass you on to another member of the support team who runs Windows and Edge…

I don’t have Woocommerce but I do have quite a few other plugins going, and after reading alot of posts here I’m fairly positive its some sort of conflict with one of them.  In the console in edge browser I get this error:

SCRIPT5022: `selector` option must be specified when initializing tooltip on the window.document object!

main.min.js (1,26414)

in wp-content/themes/Avada/assets/js/main.min.js?ver=4.4.2

Same problem in internet explorer.  Chrome, Firefox, and Safari on iOs all work fine.

I guess I could just disable all the plugins and see which one is causing the conflict?

Replying to myself is bad form I know, but I read that thread you linked to more closely and then tried your advice here:

In the templates folder of your Simple:Press theme is a file named spFunctions.php. At the very top there is an option to not use the jQuery.ui tooltips for Simple:Press. Try changing the true to false and see if that helps at all. You will probably need to clear your browser web cache before you test the change.

And of course it worked and fixed things!!  Yay! 

Excellent news. I tend to think it mght be an Avada thing. Perhaps with Woocommerce it also effects other browsers. Anyway – good to hear all is now well.