Looks like a bug with the Page Composer for REST Models with only an Insert method. As a workaround, this should work if you specify the URL Merge Condition’s parameter name in the XML for the URL Merge Condition.

1. Open the page xml editor and find your Model’s node.


2. Find the node, and set the sourceparamattribute to the name of the merge parameter in your URL

For instance here’s what the Condition node might look like, where I’ve got a url /createcontact?email={{emailaddress}}

Thanks, Zach.

For others not as comfortable with editing XML, you can trick the builder by adding a query method with the same url merge condition parameter. Once you’ve set up your condition, you can delete the query method, and the condition will stay.