If you use Citrix Workspace it could be, that you cannot use Print Screen key on your keyboard anymore. See what it is the root cause and how you can workaround this.
Print Screen is a useful key on your keyboard if you use some kind of screenshot tool, e.g. free PicPick. In PicPick by default you can use several combinations with the Print Screen key for screenshot of the current window, the screen or a user defined screen area. Sure you can define other key combinations. But especially when you use development IDE’s like IntelliJ IDEA most other keys are already mapped.
So whats the root cause here? Citrix has implemented a feature named App protection, which should block screenshots in protected windows for citrix applications. By design it should not block screenshots, if no citrix applications are open or all are minimized. Unfortunately Citrix Workspace is started with Windows 10 and block completely the PRNTSCR at least in non administrator accounts. It blocks the key in Citrix Desktops too, so you cannot run you screenshot there too. This seems to be a bug too me.
The only workaround is here not to use App protection. This feature is enabled on installation, so you habe to deinstall Citrix Workspace and maybe depending tools like Citrix HDX RealTime Media Engine before. Then you install Citrix Workspace without App protection: