Please check if you have any space or newline in the expression used on the URL of the Binding tab.
It may happen if you have copy-pasted the value from outside to the URL text box.
If the issue persists, click on the expression of the URL text box on the Binding tab and share a screen print of the same
Also, you can call the same API from the postman or any other REST-based client to check if the API works as expected and you can compare the requests
Thanks.. we are working on this.