Key Modifiers in 5.6 problem

Hi,

I have just converted my project from 5.3 to 5.6 and so far everything is running smoothly, except for one issue with key modifier inputs that do not register anymore, i.e. press [CTRL + 1].

Has anyone experienced this same issue with keypresses not being recognised correctly in 5.6? If so, please let me know how to fix this (best without using the enhanced input system).

Thx