G93 strange behavior

I have found something strange when using G93 on my CNC router that has an A axis. Below are 2 snippets of gcode that have very different behaviors:

In this snippet the last 2 lines result in what looks like rapid moves. It does not obey the feed given. My machine is not actually capable of 0.0002" movement. The smallest movement the Z can do is approximately 0.0005".

Y0. Z1.3005
G93 A178.639 F11.0982
Z1.3003 A357.443 F11.0879
Z1.3005 A360. F773.4857

This snippet behaves as expected.

Y0. Z1.3005
G93 A178.639 F11.0982
A357.443 F11.0879
A360. F773.4857

Has anyone seen this before? Have I just configured something wrong? This gcode is coming from Fusion 360. I have not figured out a way to reliably get rid of these very small Z movements in rotary tool paths. Also interested if anyone knows how to do that.

The F11,08 line should result in a move that takes about 5 seconds. Are you saying that it is faster than that?

Possibly a bug in the blending code, it is likely to discard the .0002 move in Z, but should still spend 1/11 minutes making the move.

It moves much faster than that. Pretty sure it is moving at the max speed of the A axis.

Which LinuxCNC version?

I am using 2.9 on debian 12

I can reproduce this in a sim with 2.8.4 too.

I have raised a bug report: github.com/LinuxCNC/linuxcnc/issues/2410