Have the same problem. Running both programs (DCS.exe V2.7.18 , Streamdesk.exe V5.3.1) as administrator does not solve the problem.
Left and right shift key is still recognized by DCS but not the windows or e.g. pause key.
If a previously defined Streamdeck hotkey is pressed, e.g. with L-Shift - L-Win and Pause, only L-Shift is recognized by DCS.
A complete reinstallation of the Streamdeck software did not solve the problem.