Invocation of Ultra task fails

Hello Team,

I have created a test pipeline, where using Rest post I am invoking an Ultra pipeline.
The ultra pipeline is simple, it expects the $test input and sends the result back. This is only for test purpose.

Here is the input that I provide to the Rest post snap:
[
{
“url”: “https://URL/api/1/rest/feed-master/queue/Reece-Dev/-Project/Test/Test%20Task%20Ultra”,
“token”: “xyz”,
“test”: “1”
}
]
Here is a test pipeline :

The Rest post gives an error:

I fail to understand why does the ultra pipeline throw an error when I am passing $test object to it. Here is the snap of Ultra task :

Can someone help here please?