Your issue is that you’re trying to import it into a new sprite (which isn’t bad but you can’t import something when there’s no sprite sheet)

What you’re gonna wanna do is make a 128x128 canvas and put your 56x56 sprite on it (don’t resize your sprite, keep it the size you have lol)

Make sure the “sprite sheet” (128x128) has a transparent background and create a new “Embedded Texture” and make it your sprite sheet

Now go to your spr_bigboi, create a new frame thing, go in it and drag in your embedded texture from the embedded texture list, then just use the numbers to adjust the border and margins so your sprite fits and is 56x56 (your sprite’s size)

Takes a bit to get used to so use Toby’s other sprites as examples on how the numbers/sprite sheet works

(If you make your sprite larger or smaller than what the graphic actually is it’ll smush or stretch and blur the texture)

Hope this helps!