Copying only visible cells on a sheet that has merged and hidden cells can be a bit tricky, but there are a few ways to do it. Here's one method that should work:

1. Select the range of cells that you want to copy, including any merged or hidden cells.
2. Press F5 to open the "Go To" dialog box.
3. Click the "Special" button at the bottom of the dialog box.
4. In the "Go To Special" dialog box, select "Visible cells only" and click "OK".
5. Press Ctrl+C to copy the selected cells.
6. Click on the cell where you want to paste the copied cells.
7. Press Ctrl+Alt+V to open the "Paste Special" dialog box.
8. In the "Paste Special" dialog box, select "Values" and click "OK".

This should paste only the visible cells, without any merged or hidden cells causing errors. If you need to preserve any formatting or formulas, you can select the appropriate options in the "Paste Special" dialog box.