Tilengine doesn't like certain PNGs?

[Domarius]

My level just displayed completely black - until I replaced the PNG of the tileset (tiles.png).

The problem is definitely the PNG file, I think maybe related to the palette;

• Swapping my png file (tiles.png) with one of the others from the samples, displays the level - but with the wrong tiles of course
  
• Opening one of the sample png files in Aseprite (eg. castle_bg.png) and pasting my artwork into it, then saving it, displayed my level correctly.
  
• But opening and re-saving the original tiles.png in both Aseprite and GIMP, didn't work.  They may be maintaining the original palette.
  

tiles.png was originally exported from Pico-8.  I would say Pico-8 might be doing it wrong, but tiles.png still opens correctly in every editor and viewer that I tried.

I've attached a zip of my map and tileset. Try placing it in the assets folder for the samples, and get one of the samples to load it, you'll see the blank screen instead.