Tried to fly my P4P and told I've reached my max. height but I'm only at 11 feet. Whats that all about?

It's about two things.
1.  You don't have GPS reception - perhaps you are under cover that's blocking the Phantom's skyview
2.  You have the VPS sensors turned on.

Turn the VPS off and you can get to 100 ft (but you'll be in atti mode if you don't get GPS reception.
Get out into the open and you'll get rid of all those restrictions.

p55 in the P4 pro manual has the explanation:
Height is restricted to 26 feet (8 meters) when the GPS signal is weak and Vision Positioning is activated.
Height is restricted to 98 feet (30 meters) when the GPS signal is weak and Vision Positioning is inactivated

Hi, thank you for reaching out and we're sorry for the inconvenience. Can you please clarify if you receive an error message in the application? Can you please provide us a screenshot for us to further isolate the problem? Also, can you please try to fly in a different location for us to check if you still receive the same problem. We highly recommend calibrating the IMU and the compass for us to avoid any issues. Updating the firmware to the latest version also recommended. Please keep us posted. Thank you for your continued support!

just look into your settings and see the max alt you have on your p4p