Black Boxes around backgrounds and some blocks

[deleted_account]

Hello guys.

This is my problem:

Using PGE:

These are the sprites:

Halp.

Edit: The carrot top and bottom show similar issues although they also use the right masks.

[bossedit8]

You have to replace the broken graphics' mask into different graphics that has a mask aswell. SMBX itself doesn't read mask tiles if the default graphic doesn't have a mask aswell.

[deleted_account]

You have to replace the broken graphics' mask into a different graphics that has a mask aswell. SMBX itself doesn't read mask tiles if the default graphic doesn't have a mask aswell.

Oh, I see.

[Gameinsky]

The problem is a bit difficult to figure out because it seems counter-intuitive. It has nothing to do with the masks or the graphics themselves. They are correct.
However you used maskless graphics as a base. That doesn't work. Graphics that have a square mask don't have a mask, and can't be masked.
I would suggest replacing background 1, 89, 148 and 149 instead.

[edit]
Well I got ninja'd