I've upgraded from Premiere Elements 2018 (Version 16) to Premiere Elements 2020 (Version 18). I have several projects I created in PE 2018 (in Win7) which I now would like to continue editing in PE 2020 (in Win10). When I open a project using PE 2020 which was created in PE 2018 the render function does not work. The little yellow line indicates that the video should be rendered and when I render it the rendering window opens up showing that it is being rendered but when the rendering is finished the yellow line does not turn green as it should to show the the clip was successfully rendered. If I create a new project in PE 2020 the rendering function works as it should. Any help would be greatly appreciated.
Premiere Elements is not designed to be backwards compatible. In other words, it's not designed so that you can open a project created in version 2018 with version 2020. Sometimes it works -- but most of the time you try you end up bugging up or even corrupting the project.
Our advice since version 2 of the program has always been to finish your project in the same version you started it in. Otherwise there are no guarantees.