Confirming the same issue here in MSFS 2024 SU4 with native Real-Time Online (live) traffic:
Airport: iniBuilds EGLL (Heathrow)
Traffic: Real-Time Online (native MSFS), no injectors
Symptom: arrivals are coming in normally, but I see zero AI departures (no pushbacks/taxi-out/line-ups). It’s effectively arrival-only traffic at EGLL.
I disabled the default Asobo EGLL to avoid double scenery (as recommended), and the issue persists with iniBuilds EGLL active.