Passing CSV string as API payload to run monitor

I have a monitor set up that accepts a CSV file to test different POIs with every iteration of the file. Iā€™m trying to set up a script that parses a CSV file and sends a request that includes the first 50 rows (in text/csv format) within the payload for testing on this monitor.

This request is being received by the monitor, because it is executing whenever I run the script. But it is not running with any of the sent-in iteration data.

Is this a possibility? Any workarounds for sending in manual CSV data to test with a monitor from an API request?