Transparent prefab sprite

Hi there,

I don't know why or how, my sprite prefab turned transparent. I have exactly that sprite but with a red color, that I use for the exact same thing, that uses the exact same settings and scripts, but the red one is not transparent. Also, alpha is 255.

It is invisible when I drag it in the scene and I cannot see it in game view either.
I drew an arrow to show you the object of the prefab and the icon if it is how it should look like (blue circle)

 

Update:

Apparently even in prefab view, it looks for a mask... it was set to be visible inside mask, so I changed it to none, the sprite appears...

The red one was visible because it was set to be visible outside the mask. If anyone runs over this problem, be careful with the masks.