(Solved) Major - Sequencer - Position changes without it being keyframed (+repro + project file)

When making an animation in sequencer, if you set a section to “additive”, then the object will move outside of that animation in a weird way showcased in the video below:

Since I have no keys on location, the sequencer shouldn’t move its location when entering or exiting the animation (unless I am missing something, in which case it means the editor convolutes the process for no reason) Here is the project file to see it in action (exactly what happens above):
Door_test.rar (61.3 KB)

Also a little extra, if you set “keep state” with additive animation and play it, you can mess up the animation and Undo doesn’t bring it back to where it was before.

Looking at this now, I don’t think this was the same issue we were having, when you open the Sequence, the Y location is set to 35, meaning it’s adding 35, even when there’s no keyframe. If you set that to 0 does it still happen?

The issue we were having was during matchmaking, even weirder.

I see. That makes sense then. Very weird and hard to understand that values like that can affect the animation with no tell.

What if I had multiple things being tracked, should I go check all values and compare with the original? That’s awful UX. I ll continue this on feedback.

I believe if the tracks are Additive and you don’t want to affect let’s say Location, they should all be set to 0,0,0, meaning it’s adding 0. You can also just delete the transform tracks you aren’t using.

Still weird. A value should change color or have a track on the right if the value is not the default, to help visibility. Especially when moving the door automatically created that value for me without noticing. In a complex format, it would be a nightmare to debug.