If you added in any new inputs after the downstream tools were connected, sometimes problems can be resolved by disconnecting the noodles then reconnecting them. Start from the inputs and connect the tools in the order of execution.
There are some metadata settings that occur when tools are connected. It seems like that is what is going wrong in your case, so please give that a try first, for the quickest resolution.
There are no known issues with using simple-inputs right now, but if you are still having problems, share more details. Where are you working (public server? URL? your own server?). What tool is failing, name and version (cannot see the name in your graphic)? Does the workflow execute correctly when run directly from the web browser as well, or just when executing it via the API?
We might ask for you to share a link to the workflow, or more details about your API query, if the issue cannot be reproduced, but that can be done privately if you prefer.