I3 Plus not extruding after BLTouch upgrade. (Video included of issue)

I hope someone here can help, because I am stumped.

Configuration:
Monoprice Maker Select i3 Plus
Simplify3D
Printing through USB via OctoPi
Advi++ 4.0.3 ( ADVi3pp-BLTouch3-Mainboard-4.0.3.hex)
BLTouch Smart v3.1

I printed the adapter prior to installing my BLTouch and upgrading to the BLTouch3 version of Advi++. No issues at all at this point.

I installed the BLTouch and it worked, I can perform an auto level and adjusted the zheight, still no issues. However upon changing my starting script in Simplify3D, I noticed my printer is no longer extruding. It heats the extruder and bed to their desired temp as I expect, it then extrudes 3mm of feed stock. After that it moves into position and starts my print.

The issue starts here. It extrudes about 2mm of feed, then restracts that 2mm, and it does this over and over throughout the entire print. I put a piece of tap on the filament right above the extruder and it just goes up and down, up and down, never actually extruding anything. I’ve made a video to share what I am seeing: https://www.youtube.com/watch?v=ZcGVh7mWptI

Note: if I attempt my previous gcode file of the adapter (with my old starting script), it prints fine still even on the Bltouch3 version of the hex. It just doesn’t use auto-level, which is what I want here.

I’d be glad to try anything you might suggest, and provide any files you may need to help.

Thanks!

Okay so I fixed it, but it is an odd fix considering none of you had to do this as well.

I had to add in M83 to set the extruder to relative positioning. For whatever reason the G90 at the start of the script to set everything to absolute positioning kept my E axis as absolute as well so it would extrude, then retract so it could start at 0 every time.

I discovered the issue as I was reading through the Marlin documentation on G90. It states:

This is when I realized what was happening. I quick add of M83 at the end of my starting script fixed it! I really hope this helps someone else out there.

Okay another Update. I apologize for all the comments but I think its good to clarify should another person face this.

In Simplify3D (my chosen slicer), In the Process Settings under the Gcode tab, there is a checkbox for “Relative Extrusion Distances”. If you have that checked, you cannot use absolute positioning on the E axis (Extruder), you must add M83 to your starting Gcode so it uses relative positioning. The alternative is leaving the starting Gcode as described in the Advi++ User Manual and just un-tick this box so it uses absolute.

Hope this helps someone out there. Also Sebastien, if you ever see this, thanks for all you have given back to the 3D printing community. Advi++ has given new life to my i3 Plus.

Thank you a lot.