Workflow Types; Item parameters not calculating expressions

Workflow Items that define Parameters for the User to enter information into were not calculating the 'Expression' defined on the Parameter.

Expressions for visible Parameters are now calculated upon loading the Action Workflow Item wizard, e.g., to set a date parameter to the current date.

Expressions for non-visible Parameters are calculated upon clicking the Finish button.

Parameters are only ever calculated on these two occasions, i.e., basing a parameter on an expression that references other parameters will not update that parameter as the other parameters are changed. The only way to ensure this parameter is calculated is to make it non-visible in which case it will be calculated when the Finish button is clicked.