Thumbnails in DTTG


I apologise if this been discussed somewhere else but does any one know how thumbnails are generated in DTTG?
I like the thumbnail view after touching the document count in the sidebar of iPhone and iPad but often some groups have thumbnails but often don’t and some documents don’t seem to have them even though they do in DTPO…
It’s not a huge issue but find those previews quite useful to find what am looking for.
If there is some way to cause them to refresh and generate then I would love to know.


Preview images are generated in the background when you look at groups in grid view. They are then stored for future reference. In addition, previews are synced from the Mac and kept for the same purpose.