xnview 2.50.4 (and 2.50) slideshow's "add folder" doesn't pick up ".webp" image files

[tikmok]

os: windows 7
xnview: 2.50.4, 2.50

Steps (1) to duplicate:
1. create slideshow
2. add folder with only .webp files
3. click go

• doesn't go

Steps (2) to duplicate:
1. create slideshow
2. add folder with only .webp and .jpg files
3. click go

• only .jpg files show

[xnview]

right will be fixed

[tikmok]

Thank you sir!