We had a recent instance of the release button not being available for a form. The option to reassign was there, but not release.  This happened to be an accidental duplicate submission on the part of the customer, so the form was reassigned to someone with the authority to cancel the task and the task was canceled. After that, I restarted the process from the Monitor menu and assigned the form to myself, then the release button was there? Is there any circumstance where the release button would not be available?