Change sequence frame size without layer position auto-adjusting?

Hello! I've been using Premier Pro on and off for about a year now, and I'm encountering an increasingly annoying bug (or "feature") - if I create a sequence and have animations on the position of clips in said sequence, if I realize I need to change the frame size the position tries to auto-adjust with the ratio of the previous size!

For example, let's say I make a sequence 1080x700. I start an animation on the position of a clip: I want it to move down the screen over an interval of time from (540, 200) to (540, 600). I then realize I actually need it to go all the way down to y=800, so I change the frame size to 1080x900. I go to edit the animation, but now the 200 shows up as 257.1 and when I change it to 800 it resets itself to 1028.6 (multiplies whatever value is in the y by 900/700)! At least I think that's what it's doing...

And then it shows up in that new position on the screen and I can't figure out how to make it realize the new frame size without either doing the math and tricking it into the position I want or starting the sequence over from scratch at the new size upon creation, neither of which should be necessary! Anyone know how to fix this or if it's a known bug?