Unable to export an individual sheet from a multi-sheet spreadsheet into CSV on Numbers?

By "sheet" do you mean "table"?

If you have only one table on a sheet, then you can activate that sheet, go to its "tab" at the top, select 'Copy Sheet' from the dropdown that appears, and in a new document go to a sheet tab and select 'Paste Sheet'. Then export to csv from that document.

Or you can select all the cells in the table you want to export, command-c to copy, start a new document, paste into the table in the new document, then export from the new document.

This all sounds more complicated than it is. It's quick and easy.

SG

Export as separate tables, which will make a folder of CSV files (one for each table), then delete the ones you don't want.

I think a new document is the easiest, but it is also possible to select the cells, copy to the clipboard, and run a Shortcut (which first needs to be written) that converts tab-delimited to comma-separated values, for pasting where you need the results.

SG.