Custom filament G-code - filament won't save as user preset

[michaelc]

Problem
If I make a new filament preset and save it, it persists if I close BambuStudio and re-open it.

If I do the same and add custom G-code, save it, and then close and re-open BambuStudio then the preset disappears.

Screenshots

I edit the filament and change one value (flow ratio) and save it.

Close and re-open BambuStudio, and can see saved filament:

Edit filament and add custom g-code, and save:

BambuStudio still open, can see filament:

Now close and re-open BambuStudio, filament has disappeared:

The custom g-code is:

{if curr_bed_type=="Textured PEI Plate"}
    {if filament_type[initial_tool]=="PETG"}
        {if layer_num == 0}
            G1 Z0.065 ;move z up 0.065
            G92 Z0 ;set new z as the zero point
        {endif}
    {endif}
{endif}