On several occasions I have down loaded the charts in the AIP. When planning the trip they are in the memory. After shutting down the iPad and restarting for the trip the AIP charts have disappeared. Have I some incorrect settings?

Great.
I tried to reproduce the problem today, I still have the problem (I used a different AIP) but I cannot find a sequence that will always create the problem as once the plates for one airfield have been loaded, the problem won't appear again for this airfield. !!!
If you need a video showing the problem, I could do this.
Regards
Pascal