I would like to have a help on what I am facing and also,

I would like to have a help on what I am facing and also, I would like to share a bug.

Starting with a bug, the Gcode that was made in Fusion 360 will guide my CNC to go to negative value in Z axes right after firing it up. This was solved by removing the title of the action from the Gcode. For examples, (2D Contours), (Pocket), (Morphed Spiral), and so on.

Here is my problem. I’m having trouble with losing G54 in the middle of milling process.The returned G54 value is different from where it started. In the tinyg workspace, there shows no error.

My current setting
PC; MacPro 2010
Browser; Safari
SPJS Ver; 1.94
PC; MacBook Air mid 2010 or 2012 plugged to the wall
Browser; Chrome
SPJS Ver; 1.94

The Gcode was made in Fusion 360, tweaked to prevent the first odd movement.
Anything else stays the same.

Any thoughts will help.
This is just my guess, but it may be caused by the problem that Justin Adie has currently.

Check if the screw is mounted tightly in the coupler. The only time I was losing position during job was when the small coupler screws were loosened and my ball screw did not rotate according to motor rotation.

This to me looks like a hardware issue. Missed steps or loose belts, but you never told us what kind of CNC machine you have.

On Fusion 360 CAM front, I believe there is a bug in the post processor too. In the properties section of the Post Process dialog, untick useG53. The offending gcode in the header is G53 Z[some value, usually 0]

If you still want to use the G53 workspace, remove the Z attribute manually.

Keen to hear if anyone knows the hows and whys of this command? I suspect it might work different on other CNC machines?

Thank you all for all the advices.
Yes, it was just a simple hardware problem. The anti-backlash nut’s spring was too tightened, it made the motor struggle. However, the anti-backlash mechanism that comes with the machine is too sensitive to adjust, it needed to be loose as much as possible.

I am using a cheap CNC called Eleksmill from banggood as it was my first time ever to own a CNC and decided to learn from this tiny one.

How great community this is!
Thank you very much!