every time I make a mission and try to start the app crashes, i go back hit start again and it seems to work. ipad mini 4, updated, p4pro updated.
Could you first confirm you have installed the latest app, iOS Pix4Dcapture 2.1.0 (last release 30.06.2017).
Also make sure the latest DJI GO 4 app is installed on the device besides the latest firmware of the drone.
Have you checked if the drone connection is fine in DJI GO 4 before opening Pix4Dcapture?
Do you make sure DJI GO is not running in the background (force stop) when Pix4Dcapture is being used?