Animation Rigging: Animation preview doesn't match clip used in animator

Hi, I am a beginner, and have been trying to figure this out for days now.. I tried to follow this tutorial and add animation rigging to a mixamo character and it's idle animation.

I used the preview and record features (in Animation tab) to create keyframes for the rig within a new, editable animation clip. When I playback the animation using the preview feature, it works as expected. However, when I press play, the animation is all wrong. The rig target changes position and rotation in an unexpected way.

Here is what I did:

1. Import .fbx of model
2. Import preset animation with the following settings...
   Animation Type: Humanoid
   Avatar Definition: Copy From Other Avatar
   Source: model
3. Add model to scene
4. Create animator for model, and add preset animation as "layer default state"
5. This works.
6. Create rigging constraints based on tutorial, this works too.
7. Duplicate preset animation and add to animator as "layer default state. This new animation clip is now writable.
8. Open new clip in Animation tab.
9. I use preview and record features (in Animation tab) to add keyframes for rigging target. When I playback using the preview feature, it animates as expected.
10. When I press play, it does not animate as expected.

Here are my settings:
Hierarchy:
https://imgur.com/7zzRmRC
Clip Settings:
https://imgur.com/7HU9VW9

Here is the animation from preview and from play:
Preview:
https://imgur.com/C6eVBhI
Play:
https://imgur.com/GCmH2SG

Any help would be greatly appreciated, I feel like I've tried everything and it must just be a simple toggle or something to fix haha. Maybe it has something to do with the root motion? Thank you so much!