Edit-in problem

I have been using Lightroom 5.7 with Elements 15 for some years with no problems. I have now just replaced Elements 15 with 2020 version and all is OK except the “Edit in” function. It starts as normal but does not open in Elements (even when already open) and the note appears eventually saying “Elements editor could not be launched”. However, when I press OK, the image does appear in Elements?! This process takes a few minutes. When I first tried a note appeared saying I may need a plug-in but no plug-ins are defined and no up-dates are outstanding. What do I need to do to get this to work as it should?