When animatitng an Integer using [DiscreteEvaluation], positive numbers are keyed as expected, but negative values are not keyed and actually delete any existing key on that frame..

Repro:
- Add an Int with [DiscreteEvaluation] to a script
- Add the script to a GO in your scene
- Open the Animation Window and create a new animaton clip on this GO
- Set the AW to Rec mode
- Using the Inspector, drag int value in script component to create a key
- Move time and create a few keys with different values
- Try creating a negative value....
bug: key is not created.
- Move time over an exting key
- update value to be negative....
bug: Key is deleted.

example Int:
[DiscreteEvaluation]
public int myInt;

This is a regression.
Repro in... 2022.1.0b3
Not repro in... 2021.2.0b11