Updating State Tree global parameter

I’m trying to update or change a global parameter in a State Tree task so that it can be used in subsequent states. Typically, I achieve this as shown below:



However, the same approach does not work when dealing with an Enum:



Is this a bug, or am I missing something? I couldn’t find any relevant information online.

For context, WeaponType is an Enum, and the property I want to set in the State Tree is as shown below: