I can’t see any way to reproduce this. It appears to be intermittent, but I haven’t been able to figure out why it sometimes happens. Curiously, Ctrl+Shift+R still works even when Ctrl+Shift+C doesn’t.
Ctrl+Shift+C seems to resume after a while (or the next day), but can’t determine why.
Since we are unable to reproduce this at our end, please check if you have any anti-virus solution/tool that is causing it. If you have any AV tool, then please disable it temporarily and close all the opened applications and open only SQLyog and check if the problem occurs.