It would seem that Lightroom mobile will not work with tiff files in the camera roll taken using the 'Pure shot' app. I have tried to get it to add photos from the camera roll into a collection which is set up for auto import into Lightroom but all it says is 'There are currently no photos to show'. No problem with jpegs. It can even render the initial camera roll preview for the album which is tiff. As soon as you get it to view the tiff files, it cannot see them.
Is this something that is going to be corrected in an update to the software as it needs addressing.