Thank you for this helpful reply. Answers in red below . . .

I migrated from Excel 2010. Apart from the "Declare" issue in VBA, easily fixed, it was trouble-free.

Are you using CTRL+C to copy? If so, try again using right mouse click copy and make sure you see the dancing border on the selection you're copying. Is it possible you think you're clicking CTRL+C and it's not "taking"? Just to make sure that's not it. It is definitely "taking"

Are both your source files and destination files saved in the current .xlsx format? They are both .xlsm files

When you are copying a range of cells from workbook 1, are you selecting just one cell (the upper-left-most) in your destination workbook, or another range? I think you must select just one cell and it pastes in the appropriate number of adjacent ones. I am doing this correctly, as you describe

Can you check that your destination workbook/worksheet are not protected in any way? It is my suspicion that this is the problem but I cannot find it. There are no locked cells or protected worksheets


Are you pasting where an area is blank and there are no merged cells? Or over the top of existing data? The paste area is completely blank