Yes, I confirm, it’s impossible to adjust tracked window in auto keyframe mode too. I’ve uninstaled Resolve, downgraded to v7, worked fine, upgraded once agaian to v8, and got the same problem.
I’ve got similiar problem. Normally in version 7, I tracked window, and then if was nessesary I set few keyframes with F1 on my Wave panel to adjust it’s shape or position. It worked fine, till the version 8, where after seting keyframe window changes it’s positon and doesn’t interpolate .