When putting any Input on MB4, on release it presses "M"

When putting any Input on MB4, on release it presses "M"

Hi, 

anybody encountered a similar issue?

When I use MB4 as MB4 on my Swiftpoint Z2, it functions correctly.

Whenever I put a button on it, be it a letter, number or Symbol, it presses the symbol, but on letting go, it presses M. 

Example:
I set MB4 to button "B". 
When pressing B, input is "BM"
When holding B, input is "BMMMMMMMMMMMMMMMMM"

Any idea how to solve this?