Filament start GCode not being inserted

[tommylux]

Description of the bug

The filament start g-code doesn't appear to be inserted if there are no tool changes.

Project file & How to reproduce

I have the following G-Code under a filament start g-code:
M165 A98 B1 C1

With a single model selected and the extruder set to #4, the model does not fire off the filament start gcode until like 102019 for some reason, it switches to T3(extruder 4) which should be active anyway for an unknown reason.

expected outcome: filament start gcode always fires, setting the desired mix ratio.

Perimeter extruder, infill extruder and solid infill extruder are set to 1 (though the model option should override this I think)
Support material/skirt extruder set to 0 to minimize tool changes.

Checklist of files included above

• Project file
• Screenshot

Version of PrusaSlicer

241

Operating system

Windows -10

Printer model

A20T

[rtyr]

Please provide your 3mf project file.

[tommylux]

closing issue: seems to relate to 'multi-colour paint'