Transparent background color is lost with saving a file as a gif

This seems to be new with the current beta on Steam.

Steps to reproduce:
-Make an ase file with a single normal layer, indexed colors, with the first color set as the transparency color. Fill the field with that transparent color.
-Draw something on the canvas with some other color.
-Save As > save this as a GIF file. The resulting GIF file will have lost its transparency.

If you open the new file, you will find its palette has been changed, with black colors added until index 63, and the new background color added as 64th color in the palette.
If you select that color and delete it from the palette, then save the file again, transparency is restored.

Expected behavior: The saved gif should keep its transparency.

I don’t know much, hope i can help you!

Basically the gif format to save files has a limited set of colours (256) that can be saved in the gif.
Since you can use only a small range of colours, you can’t have a detailed animation if you use a wide range of colours in your drawing that aren’t in the limited set of colours of the gif.
But that’s another thing, i believe your problem is that since gif doesn’t support alpha channels, you can’t save that transparency when you save your file.

If you want to know exactly why you have that problem you should ask to @eishiya or @BraidAcer since they know more about this topic.

(in case you don’t know what an alpha channel is here’s the definition)

I don’t think this is an alpha channel issue. GIF allows having one transparent colour, it has to be fully transparent. The first colour as transparency usually works. It’s only if OP’s transparency colour isn’t fully transparent that there would be an issue.

What version of Aseprite are you using? Do you perhaps have a background in your Aseprite file? Backgrounds, even if they’re hidden, have been known to mess up GIF exports in Aseprite. Try deleting the background before you export, if you’ve got one.

I am using a single normal layer, there are no background layers here. My aseprite version is 1.3 beta 5, x64

This is not an issue of me using the wrong colors, either. I have been using aseprite for years, this is a recent change in how the program behaves.

I recorded a short little stream to illustrate the problem better, hope this clarifies the problem: