Do you have to go up 20mm??
(also you have an error on the second line, take the space off Z =, should be Z=
Anyways, check my video description again. I just added one more option. if you have latest marlin, like 1.1.5+ i believe, you can use the advanced pause feature instead and that has an option to bring up the Z. I would use that instead of having to add a bunch more code manually. Reason it didnt work for you, its because you have to set relative and absolute positioning when doing that, otherwise, it wont work.