That’s frustrating, especially if it was working fine before. Sometimes these tools break after updates and it takes a while for fixes.
If you just need a quick workaround, you might want to try an online converter instead of relying on the software. Some of them handle transparency pretty well and don’t require installation.
I’ve used a browser-based tool recently where you can upload a PSD, preview it, and export it as PNG while keeping the transparent background intact. It even lets you check layers if needed.
You can try it here if it helps: https://psdtopng.com/
At least until Pixillion fixes the bug, this might save you some time 👍