G29 Bed Leveling not working

[Foxtrix 1]

Hello! I have been struggling trying to get my bed probing to work on my ender 3s1! On my printer the probe is working perfectly, and I have my calibrated my Z Probe position on the bed and I have made a 3 x 3 mesh. Just when I start a print my probe goes to the middle and probes once and goes to the side and starts printing! What do you think the problem is? Thank you for reading this! 

Start GCode: 

; Ender 3 S1 Pro Custom Start G-code
G92 E0 ; Reset Extruder
G28 ; Home all axes
G29 ; ABL
G1 Z2.0 F3000 ; Move Z Axis up little to prevent scratching of Heat Bed
G1 X0.1 Y20 Z0.3 F5000.0 ; Move to start position
G1 X0.1 Y200.0 Z0.3 F1500.0 E15 ; Draw the first line
G1 X0.4 Y200.0 Z0.3 F5000.0 ; Move to side a little
G1 X0.4 Y20 Z0.3 F1500.0 E30 ; Draw the second line
G92 E0 ; Reset Extruder
G1 Z2.0 F3000 ; Move Z Axis up little to prevent scratching of Heat Bed
G1 X5 Y20 Z0.3 F5000.0 ; Move over to prevent blob squish

 

[rburema 26]

I don't have any experience with Enders, but since they use Marlin, G28-G29 combo as described should work. Is your firmware up-to-date?