It Appears that the "G28 Z Forbidden" is given when you home Z while At Home.
While using OctoPrint If I am at home and home Z in OctoPrint I get the "G28 Z Forbidden".
If I first home XY and then home Z in OctoPrint it works fine.
While using OctoPrint If I am at home and home Z in OctoPrint I get the "G28 Z Forbidden".
If I first home XY and then home Z in OctoPrint it works fine.