Blank frame

It’s not working. The pop-up window shows, but it is blank. I tried different browsers. I do use quite a few plugins, so some conflict is possible, I guess. If no direct solution from your part, I will try to work out where the conflict may lie, if there is any. I really want this to work, would be very useful for me for people to send in updates.

https://wordpress.org/plugins/gourl-spelling-notifications/