1.4.0 - use filter - 'Focus Peak' does not work on image with alpha channel

[user0]

XnView MP 1.4.0 64bits
Windows 64bit (22H2), display resolution 3840x2160, win scaling 150%

Use filter
'Focus Peak' does not work on image with alpha channel - image became fully transparent

[xnview]

where do you have focus peak???

[user0]

where do you have focus peak???

Viewer mode
1. open any .png with alpha
2. goto Filter menu (on Toolbar) > Use filter...
3. apply '8. Focus Peak'
image will became transparent

[xnview]

ok, i can reproduce

[xnview]

it depends on the image, filter is applied on alpha channel too