Sprite.textureRect returning Rect.zero for SpriteAtlas-packed sprites?

Unity 2020.1.14f1

Since I have insufficient privilege to that other very nice thread, let drop my comments there :

- https://forum.unity.com/threads/spr...t-zero-for-spriteatlas-packed-sprites.583564/
(Amazing thread by @Arthur-LVGameDev)

To complete what is said in that thread, it works while disabling AllowRotation and TightPacking.

If you make a single sprite and it's sprite.packed=FALSE, no problem with the sprite.textureRect.
If you do the same with a packed sprite in runtime with sprite.packed=TRUE, the sprite.textureRect returns zero for all.

If !Applictation.isplaying then sprite.texture still target the unpacked sprite.