The same box is created when trying to save the individual layers as PNG images.
This a recent bug that occurred both in 1.1.13 and 1.2.
If this is not a bug, what can I do to fix it?
Hi @ClyffeSmash, it might be caused by some “hidden” pixels that reappears when the new palette entry is added. Here a little video showing how this can be reproduced (we draw with a new color that then we remove, but then we add it again, the index data in the image is still present):