Hello Kubris,
One of the reasons this might be happening is that these key combinations are intercepted on a lower level by different software (or some driver utilities, those for your graphics card).
Other remote desktop apps, such as the one built into Windows, [censored] , etc... pass all KB shortcuts by default (except for Ctrl+Alt+Delete, obviously) - so having that not work in Remote Utilities was a surprise.
Could you reproduce the problem with other software
on the same local and remote computers where Remote Utilities is installed? Please, note that issues of this kind are machine-specific - what happens on one machine won't necessarily happen on another.