Heightmap issues! {Solved, Please lock!}

[vxxv]

(I'm relatively new to forums, and english isn't my first language; my apologies if i do something wrong-!)
So... today i was going to make my first map!! I was super excited buuut things didn't work as i thought they would.
I made this map :



And made sure it was all a-okay for exporting it into the game (one layer, grayscale mode on GIMP, PNG format, 513x513 size, saved on 'terrain' folder)
However, when i went into the map maker and tried to export it, the game would just freeze and stop responding (not crashing, but i had to close it anyway)
I thought maybe the game was having trouble with it since i used a textured brush. So i made another map just to test it out, a lot less complex this time, without any textured brushes and with all the required settings for it to (supposedly) work :



And the game still stopped responding when i tried exporting it!
i understand the game may need time to load properly when you export a map, but mine would just freeze completely and stay like that, clicking anywhere on the tab would just break it further.

Does anyone know how to sort this out? I'd be eternally thankful! ;w;


EDIT : sO UH i managed to figure it out by myself! Seems like i forgot to remove the ''Alpha Channel'' thing on GIMP.