Unable to get event id on calendar when event clicked

Wappler: v3.9.3
OS: MacOS
Server Model: PHP

I’ve got a calendar working nicely and now trying to do the click action on an event. I have the Event Click action on the calendar and am trying to set the select for a Data Detail so I can show everything in a modal but the bindings aren’t showing (see screencast).

When I click on the triangle to open the Source fields, it just disappears.

I’ve tried manually entering what I think it should be but it’s not working.

Is this a bug? How can I manually enter the code to get this working in the meantime?