No Reset

There are two things you need to check. First, please ensure that the editor setting Default Create Reset Tracks is turned on:

To check this go to Editor -> Editor Settings and then navigate to Editors -> Animation.

This setting controls if the reset animation tracks will be created automatically by default when creating a new animation track. It should be on by default in a fresh install of Godot.

Also, when you first add a key to some animations, before creating an animation track and inserting the keyframe, Godot gives you a checkbox asking you if you want to create a corresponding reset track. You need to make sure it's checked as shown below.

If the checkbox above was turned off, then the RESET animation will not be created.