Simple modification not applied to new keyboard

[giallu]

I attached a new USB keyboard (custom DZ60 build from KBDFans, Vendor ID: 0x445a, Product ID: 0x2260) and the one modification I have in configuration (caps_lock to non_us_backslash) is not working.

I tried to add the modification in both the "For all devices" or in it's own section, same result.

The device has "Modify events" flag on:

Any idea why this is happening or pointers to where to start diagnosing the issue?

KE v14.3.0, OSX 13.3