The file types in the dialog boxes are too restrictive.
In the import dialog JPG and TIF files are permitted, but not JPEG or TIFF. The definition of an image file just needs to be loosened up a bit.
In the export dialog the save as type is fixed as PDF. It’s not possible to see All Files. So when converting “averyverylongfilename.tif” the user has to type in “averyverylongfilename” rather than being able to select All Files, pick “averyverylongfilename.tif” from the list and overtype “tif” with “pdf”.