You can use two variables to obtain the values of the attached file or image field in a string separated by commas.
Axp_AttachedFiles - is a variable that will contain the list of files (header attachments) attached as comma-separated strings.
Axp_LoadedImages - is a variable that will contain image fields as comma-separated strings.
Using this, a valid expression can be defined as shown below...
iif((Axp_loadedimages # {}) & (Axp_attachedfiles#{}), {T}, {File/image is not loaded})
