gcode commands in octoprint: Z moves ignored?
Photo Credit: Courtesy of 3DStockPhoto ( image)

Thanks in part to Tom van Der Zanden, I got a working version, which I'll paste below to add some actual value to this question! The G1 XY coordinates for each position are for near the corners on a 220x220 bed, but leaving enough room to access a screw in the corner of the bed if you need to (I don't anymore, but my printer did initially) - for different bed sizes, you'll want to change them. Add to ~/.octoprint/config.yml

controls:
- children:
  - commands:
    - M140 S50
    - M104 S190 T0
    name: Preheat
    type: command
  - commands:
    - G91
    - G1 Z10
    - G90
    - G1 X30 Y50 F9000
    - G28 Z0
    name: Front Left
    type: command
  - commands:
    - G91
    - G1 Z10
    - G90
    - G1 X180 Y70 F9000
    - G28 Z0
    name: Front Right
    type: command
  - commands:
    - G91
    - G1 Z10
    - G90
    - G1 X30 Y160 F9000
    - G28 Z0
    name: Back Left
    type: command
  - commands:
    - G91
    - G1 Z10
    - G90
    - G1 X180 Y160 F9000
    - G28 Z0
    name: Back Right
    type: command
  - commands:
    - G91
    - G1 Z10
    - G90
    - G1 X100 Y100 F9000
    - G28 Z0
    name: Centre
    type: command
  layout: horizontal
  name: Levelling

<a href=enter image description here">