Another method..
On the dropdown create a custom property called displayvalue.
On the dropdown value prop, right click and add a change script.
data = self.props.options
for row in range(data.getRowCount()):
if (data.getValueAt(row, "value") == self.props.value):
self.custom.displayvalue = data.getValueAt(row, "label")
break
That should then update the custom property with the label.
Credit goes to the below, there was another script that took that code a step further that may help.