RH not reporting correct position

[ruggb]

Marlin-bugfix-2.0.x.9a515cb
RH 2.1.3
not reporting position after this script
G28
G0 Z20

It works perfect EXCEPT RH reports Z is at the offset -0.10

RH log
N11 G28
N12 G0 Z20
X:0.00 Y:0.00 Z:-0.10 E:0.00 Count A:0 B:0 Z:-80
ok
ok

If I then do a G0 Z30 RH reports Z=30

If I do home Z or home all Then do a G0 Z20 manually
RH reports the correct Z=20.

RH log
N11 G28 z0
X:0.00 Y:0.00 Z:-0.10 E:0.00 Count A:0 B:0 Z:-80
ok
N12 G0 Z20
ok

where is the problem?