Topic Odd bug: Cannot use AltGr Shift M

For some reason, it seems impossible to specify a rule for AltGr Shift M. The following is a complete .kmn file that demonstrates this:

store(&VERSION) '9.0'
store(&NAME) 'Demo of AltGr Shift M bug'
store(&LANGUAGE) 'x0409'
store(&WINDOWSLANGUAGES) 'x0409'
begin Unicode > use(main)
group(main) using keys
+ [SHIFT RALT K_M] > '*M*'
+ [SHIFT RALT K_N] > '*N*'
+ [SHIFT RALT K_B] > '*B*'

When installed and tested with Keyman Desktop, AltGr Shift N and AltGr Shift B work as defined, bur AltGr Shift M does nothing. Tested with Notepad, among other things, to make sure that the cause is not some program that allocates AltGr Shift M to its own use.

I tested the program here and had no trouble with AltGr+Shift+M.

Can you make sure there is not a Alt+Shift+M hotkey assigned in Keyman Configuration, Hotkeys tab?

There may also be another utility program using that key combination as well; some display driver utilities have hotkeys assigned for all kinds of things.