I am having a similar issue with saving png files as transparent.
1. I created a transparent document at the start.
2. Selected Export, turned switch off by matte background, selected png and no matter what I do it saves with a white background, even when I do it by selection, and selecting selection without background.
3. The screenshots of the picture were loaded into procreate after exporting from designer but this is what it looks like. Procreate supports png files.
I am including screen shots of what it looks like when exported.
Any help would be greatly appreciated.
Thanks,
Cheryl