After I calibrate everything is green and the Inspire flies great.

But I'm a bit worried that I can't usually lock in a home point manually.

When I try to do it in the IOS app it usually just says "CAN'T LOCK IN HOME POINT" with no explanation.

Should I be worried that it might not be properly locking in the home point when I calibrate?  I would think it would bring up a NOT SAFE message if so.

Once, when I tried to select the remote instead of the Inspire it said WEAK GPS SIGNAL TO REMOTE which at least gave me a clue, but the Inspire had strong signal yet still failed.

Any thoughts or am I missing something?

The home point locks in automatically in GPS mode once the motors spin up.You should check for the H on the map section in the app to make sure that it has locked the home point prior to lifting off. If its in GPS whilst your flying you can change Dynamic Home point in the app if you want to move from the original Home point in the take off area (either the Aircraft or RC unit).

This happened to me today,using an iPad air 2
I was within 2 metres away front the inspire,had done IMU Calibration,compass calibration etc,all seemed fine,I started the motors and tried to set my home point,but it gave me the error WEAK RC SIGNAL and I was within 2 metres from the craft,so I disconnected the IPAD AIR 2 and connected my ANDROID device,it allowed me to set my home point immediately
I contacted DJI support
All they said is this is very strange
They said they will get back to me

have you do update DJI APP for IOS in version 1.0.1 update is avalaible since yesterday

Yes, on latest version 1.0.1.

I know the home point locks automatically, was just going through all the commands and was concerned when it wouldn't do it manually.

Should I be able to do this or is this normal since it's the same point automatically set?