When I add the "collect payment" option to the message start event in the *new* forms designer in version 11 the plug in does now show. If I select the option to "collect payment" and complete the form and then view the progress of the form in Monitor, there is a message that no payment amount was specified. It would appear that the plugin exists in the background of the form but not displaying. 

When I add "Collect payment" in the classic forms designer it works as expected. 

I am not sure if this is by-design or a bug.