Behaviour to clear the value of a selection list field does not work in JSD portal

Issue:

When mapping a behaviour to a Service Desk project, using .setFormValue(null) on a single select list does not perform as expected

Steps to reproduce:

Create a single select custom field (Field A) with 2 options, 'Yes' and 'No'
Create a second single select custom field (Field B) with any number of random options
Configure a Service Desk Ticket screen to include these fields
Create a Behaviour that is mapped to the Service Desk Project using Service Desk mapping, and apply the code below
Go to create a ticket, select a value in Field B, and then select 'No' in Field A

Expected result:

Value in Field B should be cleared

Actual result:

Value in Field B is no cleared

Code used:

Behaviour applied to Field A

def SelectionListField = getFieldByName("Field B")
def YesNoField = getFieldById(getFieldChanged())

def selectedOption = YesNoField.getValue() as String
def isYesSelected = selectedOption == "Yes"

if (!isYesSelected)

{ SelectionListField.setFormValue(null) }