In certain circumstances, when you copy/paste a panel into another dashboard, you may find that the new panel is blank.
This will happen most often if the dashboard that you copied from has variables defined that the panel relies upon. For instance, if a panel relies on $host to be the address of your server, but the destination dashboard doesn't have that variable, then the panel will copy, but be blank.
Below you'll see the issue:
Fixing the issue requires replicating the variables in the destination dashboard. (Unfortunately there is no method for copy/paste, so they must be regenerated.). In any dashboard, you can see the variables in Dashboard Settings → Variables:
Replicate the variables in your own dashboard:
And, once you save those new variables, you should find your copied panel now works: