Transport bug? My ACU fell out

occurs approx 12:35 into game, blue player.

The ACU never finished loading before you gave the transport a move order. Might want to make sure you give a Shift+Move order next time to avoid premature departure.

Why can the acu not continue it's attachment to the transport when it's in the air, and when the transport begins to move.

It was nanoseconds from the transportation unit deploying it's acu shoulder attachment mechanism/some kind of magnetic attachment/or gravity assisted attraction device.

Its probably in the small window when a unit gets sucked into the transport but isnt clamped in yet so it doesnt count as being loaded in the transport

Or atleast thats my guess