I found that my request object had 1 trailing comma which caused the json to be invalid. Version 2.2 ignored this comma and version 2.4 does not and writes an error to the log. Once that comma was removed, the 'RawRequest' dialog showed up and worked as expected.
However, there are still issues using "Select Content" drop-down within the asserion dialog. I will not use this anymore. Instead use the right-click context menu "Get Data" and use that dialog to achieve the desired results.