Hiyo, figured I'd go ahead and record and upload this since I've had it happen three times now out of the eight or so times I've played the level in the past few days(I am trying to do a deathless legendary run of the mod with some skulls on) -

So essentially the bug is, after you clear all the enemies when Cortana tells you 'I need you to upload me into the control systems. The terminal is located next to the main view screen.' - even though all the enemies are dead, and even though you are in the trigger zone - it doesn't start the cutscene until you leave the room and then re-enter it like how I did at the end of the clip.

https://streamable.com/3mptfk

I put the word 'softlock' in quotations because after one learns how to get around it and trigger the cutscene, it's not that big of a deal to deal with - but I can imagine someone on Legendary with the Iron skull enabled as I have it and getting annoyed that they might have to restart the level assuming they don't know/can't figure out how to get the cutscene to trigger and believing it's just straight up soft-locked.

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I think what might be happening is, I am passing the trigger that checks whatever condition there is for the cutscene to trigger before Cortana activates it while there are still enemies around, and I am killing the final enemy *past* the trigger zone, so I have to leave the area and step past across the trigger threshold to get it to re-execute its checks or whatever it does to determine if it should play the cutscene or not*I dunno; from my understanding ♥♥♥♥♥♥♥ around with making Halo 3 mods that just makes sense to me. Probably not very helpful tbh. sorry.)