"an error occurred while trying to add the selected project to the batch" AME 2018

Yesterday is the first time something like this happened to AME. Whenever I try to export something it says 
"an error occurred while trying to add the selected project to the batch" As the screenshot below shows.
However, Yesterday I kept trying over and over again until it worked perfectly, but today it doesn't want to work no matter what. Does anyone know any information about this?