I have used the excel importer for a while and it worked quite well. Now, I have some trouble after updating to 7.18.1. https://forum.mendix.com/link/questions/91739 When I try to create a new template by excel, the pop-up opens, but the file manager does not. So I cannot select an excel file. The file manager does not work in the "upload file" section either. I suspect, there is an issue with the file manager widget. But I am not 100 percent sure. Any help would be great.
Have you set the correct system user roles to the module user roles?
Did you try and upgrade the Excel Importer module from the AppStore. Could be that there's a newer version available.
Paul Ketelaars - Deprecated
A bit late but here goes if someone reads this at a later stage; I came across this some time ago as well. For me it ended out being a bug in the atlas framework that was fixed in a hotfix in v1.1.3. Make sure you have the latest Atlas Framework if you are running 7.18+