1.5.0 - viewer - diagonal scroll does not work

[user0]

XnViewMP 1.5.0 64bit
Windows11 (22H2), display resolution 3840x2160, win scaling 150%

Viewer
diagonal scroll does not work

To reproduce:
1. goto Settings > interface > Keyboard
- set Up/Down to "Scroll up/down"
2. zoom-in image in Viewer
3. press ← and ↑
nothing happens, same issue with other directions

Expected behaviour
scroll diagonally ↖ (eg, like in FastStone)