I have found if I share (from other apps) several items to DTTG4 (in my case all PDFs) then try and open DTTG it starts briefly then closes/crashes/shuts down. I see the DTTG icon and it then vanishes. If I reboot my iPad then DTTG4 opens fine and the items I shared are there.
It is only slightly annoying, but I have reliably seen it several time now.

