Tangential knife A-Axis turn command not getting included in applying height map

[vinevinz]

Describe the bug

Before I describe the bug, I know standard GRBL cannot control 4 axis simultaneously. My board is MKS Tiny Bee with FluidNC (apparently works great with this software). The CNC plotter has XYYZA motor all Nema17.

So, I upgraded the machine to tangential knife instead of drag. I'm using rotary cutter directly attached to A axis motor (works like charm).

Problem is, cutting mat is not that flat, probing height map results got me ~0.6mm difference from one edge to the other. As I'm applying the height map to G-Code, the A axis command actually getting removed.

Is this a bug or just the feature not implemented? Or maybe I am doing it wrong, bcs honestly I'm using 3d printer bed leveling logic here (it looks very similar anyway with klipper leveling).

I'm trying to cut circle (has not been successful yet due to uneven flatness issue)

G-Code screenshot attached

To Reproduce Steps to reproduce the behavior:

1. Load circle SVG, tangential knife enable on A-Axis
2. Probe Z and height map (I am using 2 probe here, first for G38.2, second just limit switch for height map)
3. Height-map = Z-offset -1 (my probing tool offset), max value 0.0
4. Apply map
5. New g-code generated without A axis

Expected behavior G-code includes A-Axis?

Screenshots Original G-Code

Applied height map G-Code

Other example, A-axis turn command without lifting knife getting omitted when applying height map(this is untested code, please ignore for so much knife lifting)

Applied G-Code

Thank you!