The issue may be caused by the following:

• Because you took a second or subsequent photo, a document type cannot be changed in photo-taking mode.

• [Always save to same service] is set to on in the [Select cloud storage services] screen

• When you take a second or subsequent photo

  For a second or subsequent photo, the document type for the first photo is still set.

  To change the document type, tap [Send] to upload photo images that you took to a cloud storage service.

  After the photo images are uploaded, changing the document type can be done until the time you take your first photo.

• When [Always save to same service] is set to on in the [Select cloud storage services] screen

  After you set [Save by document type] to on in the [Select cloud storage services] screen, you can change the document type in photo-taking mode.