There may be a mechanic missing at this time, but the keybindings seem to not be accurate.
C is set as Hide, but this holds breath?
The only way to hide is by clicking the toggle button with your mouse.
X is set as Hold Breath but does nothing in later missions?
Also the reliance on both mouse and keyboard at different times is a little disconnected. Expected, tap [F] to be able to continue a text message (instead of mouse click button), like you do with dialog. As pointed out above, you must click the toggle to Hide (I think that's the mechanic), while watching out for detection level it got difficult to remember what keyboard button or mouse button to click in certain circumstances. You can click all the buttons with the mouse, but diverted too much attention from the surroundings and found myself many times not knowing what to look at; buttons on the bottom, animations, detection, or recording status.