FL MIDI Out plugin(s) instances do not require being routed/assigned to the mixer when using playlist Track Mode - which currently does not seem to account for this.
When using a MIDI Out in Instrument track mode, the wizard sets ...
FLStudio installation folder. e.g. CD C:\Program Files (x86)\Image-Line\FLStudio 21. Then enter: All projects in a folder (including sub-folders) using a complete path - FL.exe /R /Emp3 /F"c:\src\", where c: is the target ...