Why does 'Keep Only Set/Pinned Data' not reduce output to a single item?

I am trying to trim the output from previous nodes so that I only pass one variable to an HTTP request. Currently, even after using the Keep Only Set option in the Set node or pinning the variable, the output still contains 8 items, resulting in 8 HTTP requests rather than one.

The expected behavior is to have a single output item (with one or two variables), with all extra items removed. However, the JSON output shows 7 empty braces, meaning the node still produces 8 items in total.

What I have tried:

• Using the Keep Only Set option in the Set node to declare my needed variable
• Pinning the variable to ensure only it is passed along

None of these attempts reduce the output count, so I’d appreciate guidance on how to remove the extra empty items and output only the single desired item.