[BUG] Crossfade Spring transition with duration flickers back to initial state at end

This cropped up in #1023 , but appears to be a separate issue. Here’s a recording:

https://user-images.githubusercontent.com/159500/113273257-c3c72200-92dc-11eb-8fa7-fde2309a87a0.mov

CodeSandbox reproduction of the bug

https://codesandbox.io/s/framer-motion-330-issue-with-layout-animations-forked-xjz75?file=/src/App.js

After some trial and error, I see that it strongly depends on the type of transition:

Works:

const transition = {
  type: "spring",
  stiffness: 400,
  damping: 50
};

Also works:

const transition = {
  duration: 1
};

Doesn’t work:

const transition = {
  type: "spring",
  duration: 1
};

This is not a new issue by the way, I found it happens in framer-motion@3.3.0 as well, so it’s probably not related to layout projection but to transition calculations.

[mattgperry]

Hmm probably not at the moment, good point. For the border radius it’s just more predictable to always get it from the same place, the internal motion values, rather than measuring from the Dom

[mattgperry]

It is related to the crossfader by the looks of it, I’ll take a look next week tho