Sorry that you cannot add images from Fujjifilm XT3 to Lightroom on your iPad using the "Add Photos> From Camera device" option.
Which exact version of Lightroom are you using on your iPad? Please check that you have the latest version installed.
By any chance, do you have any image which is Read Only or Locked on the Import Source? Also, can you check if Lightroom has device access enabled? Go to iOS Settings.app > Privacy > Files and Folders > Lightroom and see if that switch radio button is on?