Just to note I have been getting my bloodpressure up on a small issue Animate seems to have. Simple situation, I have a dot on a map I'm scaling up. I start off creating the dot at the size I want it to end at, make it a symbol, add keyframes and scale to 1x1 and add a classic tween. The strange thing is it seems to pop it's position incorrectly on the last keyframe.
A bit of fiddling and I got to the point I copied the 1x1 small version back into the end frame and scaled it to the size it was ment to end at. Thats when I noticed the anchor point had moved. What a pain. So now I'm doing the same, note the size I want it to end and then shrink it to 1x1, keyframe and scale the end back up again. The "messed-up" anchor is now the same in the small and full versions. Fun, extra work and working backwards.
I'm working in a Canvas and I did notice the x/y positions are fractions (I tested with whole numbers but it does the same). Version is 21.0.8. Example attached, but it's easy to replicate. (Scratch that ... example FLA was removed by the system as it's content type didn't match.)