Crayons event handler only firing once

I am using the Crayons environment on a custom installation page. On the page there is a button to open a modal form which is triggered by the relevant call in the event handler bound to fwClick event on the button.

I can click the button and everything works on the first occasion, but when I click the button for a second time, the event handler is not triggered.

The event handler includes the following code:


I have tried various permutations of code to signal the completion of the event handler. Running the code through a debugger it appears the low level event handler is being called, but somewhere in the crayons event library dispatch routine is not making a call to my event handler.