As far as the home point recorded, the only way I am aware of is when it is stated off my iPad. If I dont here that chick tell me that home point has been recorded then I dont take off. It always happens after I reboot. If there is another way to check that I would love to know it.
It would be very unusual for the Phantom to not record a home point before takeoff.
The only situations I've heard of that happening would be if the pilot takes off prematurely or the Phantom is in a bad location with the sky view blocked by buildings, tree cover etc.
The homepoint is recorded by the Phantom itself so rebooting the tablet shouldn't make any difference.
I wonder if it might have been a case of the volume on your tablet turned down?
If you looked at the flight record for those situations you could see if it had actually recorded a point but you weren't aware of it.
You can see visually on the app that the HP is recorded.
This screenshot shows my Phantom under a roof that is blocking sats.
Note the Distance is shown as N/A because there is no point to measure the distance from.
When your home point is recorded, the N/A is replaced by a distance from home and until takeoff, this should be a very small number ... like 0 or 0.1 metres.