Command prompt gets stuck and continues on enter key press
The other answers are wrong! The Windows console has a separate mode called "mark mode" for selecting text. In that mode the screen will be frozen, texts will go into the buffer and if the buffer is full the running process will be blocked
If quick edit mode is enabled (by default it's disabled in older Windows but enabled in Windows 10) then clicking inside the console window will activate mark mode and result in what you observed
It's very easy to accidentally click the console and stop the command. When you press Enter or Esc the selected text will be copied to clipboard and mark mode will be exited, therefore the process will run again. Priority is absolutely irrelevant here because if the buffer is full then the process is blocked forever until you exit mark mode, regardless of the priority. The console does nothing to change the priority when there are some inputs. Try opening an app that outputs a lot of data in the highest priority and click the console, the app will still be blocked indefinitely even if the CPU is in idle
Here's an example of QuickEdit mode setting in Windows 8 console:
To fix this you can disable QuickEdit mode if you don't need it. In this case copying will be more troublesome because you must open the context menu, select Edit > Mark. You can also disable QuickEdit mode by setting ENABLE_QUICK_EDIT_MODE with SetConsoleMode() if you're writing your own console application
See also
- How and why does QuickEdit mode in Command Prompt freeze applications?
- What does it do exactly if I click in the window of cmd?
- Turn off Windows 10 console "Mark" mode from my application
If other processes are sucking all the cycles and have a higher prio, then your process might be stopped. A user input might just give it a prio boost, so it starts again. See Microsoft Docs at https://docs.microsoft.com/en-us/windows/win32/procthread/priority-boosts for more information.