Just measure all the tools again, then they all will have the same Z position. If the tool eye is not repeating (different measurements at each time), then you might have some problems.
I hit in measure sensor(to measure tools) by drill on rapid feed(approach) because I introduce bad length(to short) of tool. Operator said that sensor show bad length about 0.8 mm. in Z axis. That machine is Mori Seiki NH 4000. I don't know if I damage sensor. Mayby it's has some safety lock? If sombody could help me I will be graceful. Sorry for my language:/
Just measure all the tools again, then they all will have the same Z position. If the tool eye is not repeating (different measurements at each time), then you might have some problems.