Masks don't seem to work?

[Marina]

I tried creating some custom graphics (don't judge me, I'm bad at creating graphics from scratch) and I put them in the level folder and everything, and everything seems to be fine, except for these corners

Spoiler: show

Their masks don't seem to work like they're supposed to. I know that some graphics don't have masks and therefore can't have custom masks, but I know that the corners I used for my custom graphics (the SMW Grass corners) have masks, so I don't see why my custom masks won't work.

Am I missing something really obvious here? Here's a screenshot of the folder

Spoiler: show

[bossedit8]

Are those Masks on .GIF FIles? SMBX Only read Gif Files and not with anything else.

[Emral]

Only tiles which originally had a mask can have an altered mask.

[Marina]

Only tiles which originally had a mask can have an altered mask.

Yes, I know, they have a mask, they are (like I already explained) the corners of the SMW grass tyles, which have masks

Are those Masks on .GIF FIles? SMBX Only read Gif Files and not with anything else.

Yeah, they are .gif files

[Chad]

What does the mask look like? The extra black pixels in the screenshot need to be white on the mask. In fact, you may not even need a custom mask, because the corner tile appears to be the same shape as the original.

[Marina]

What does the mask look like? The extra black pixels in the screenshot need to be white on the mask. In fact, you may not even need a custom mask, because the corner tile appears to be the same shape as the original.

Yeah, they are white on the mask, but maybe you're right, I just won't use a custom mask at all, anyways, thanks for trying to help

[Shadow Yoshi]

Have you tried saving your level and then closing/reopening the editor? I'm assuming you have, but I just want to be sure you know you have to save the level before the graphics update.