Z offset in Marlin is not working recently
I have the same problem. You need to check your G-code to detect where's the problem.
Try comparing the G-code file with different values of the Z offset.
In my case it looks like this:
No offset
;LAYER_COUNT:107
;LAYER:0
M106 S255
G1 F300 Z0.84
G0 F6000 X124.645 Y78.208 Z0.84
;TYPE:SKIRT
G1 F300 Z0.44
G1 F1500 E0

With offset (comments made by Cura)
;LAYER_COUNT:107
;LAYER:0
M106 S255
G1 F300 Z2.06 ;adjusted by z offset
G92 Z0.84 ;consider this the original z before offset
G0 F6000 X119.093 Y42.498 Z0.84
;TYPE:SKIRT
G1 F300 Z0.44

I hope this helps.