1.11.5 - Inconsistent transparency on thumbnails of various files

[woot000]

Recently updated to XnView MP 1.11.5 on Windows 11 24H2, and I've noticed some thumbnails don't have transparency depending on what type of image they are.

For tab thumbnails, PNGs with palettes (256 colors or less) render transparency as white, but PNGs with 8/16 bits per color (more than 256 colors), WEBPs and JXLs correctly render transparency.

tab thumbnail transparency.png

It's the opposite for viewer thumbnails. Paletted PNGs render transparency with the checkerboard, but PNGs with 8/16 bits per color, WEBPs and JXLs incorrectly render transparency as black.

viewer thumbnail transparency.png

The catalog is enabled, but I do not have thumbnail caching enabled.

catalog and thumbnail settings.png

I have attached the images I used above in a ZIP file for reference.