XnView Software

I have some 32bit color depth pictures in avif and png file format in one directory. I opened the folder in browser window and the thumbnails of these two files have graphic errors. I can rebuild the thumbnails of these pictures and the results are perfect. If I open the same folder in browser window again,
I will see the same graphic errors.
.
1. AVIF (32bit color depth) => errors
2. PNG (32bit color depth) => errors
3. AVIF (24bit color depth) => no errors
.
I can open all files in fullscreen mode and all pictures have no graphic errors.
.
My XnViewMP program use the webp file format for catalog caching.
If I use the jpeg quality (low or high), everything is fine.
.
Is it possible to modify the catalog system for webp quality setting?
If you use 16 or 24bit color depth for webp thumbnail cache file, we would'nt see any graphic errors.
.

even after a thumbnail rebuild?

I tried a thumbnail rebuild and they looked right.
After that I browsed to another folder and moved again into the directory with the 32bit avif/png files.
The thumbnails get the same graphic errors again.

i've tried with 1.02 & 32bits PNG, and no problem

Here is a small video for you, which shows the problem.
It is a mp4 video file (HEVC encoded).

could you send me the 3 files?

Here are my test files.

Thanks to your detailed description I can reproduce the problem.
It occurs when alpha is blank

Fantastic! Thank you!

This problem is supposed to be fixed in XnView MP 1.3.0. Please check and confirm the bug fix here.