Appian User Record Type - Related Action error

Update #1: I still wasn't able to get this working with a!recordActionField(), but instead I included it by adding the Related Action shortcut on the view configuration. This seems to be a bug with the User Record Type.

Update #2: Passing the UUID with the user() function as the identifier was the solution! Thanks Dan.

I created a custom view for Appian's User Record Type (the same record that displays when you click on your user icon and go to "Profile"). I have a related action that takes the user to a custom form to update some details. When I trigger the related action using a!recordActionField(), the following error is thrown and the process does not start:

An Error Has Occurred The specified User related action does not exist or you do not have permission to view it.

However, when I trigger the same related action by visiting the out-of-the-box "Related Actions" view on the User Record, it starts the process successfully. Because it works from the Related Actions form, I'm inclined to think that the object security isn't an issue. I double checked the security on the Process Model, the User Record Type, and the interface.

My hunch is that I'm passing the wrong value for the identifier, but I couldn't find documentation on what the proper identifier would be for the User Record Type. I've tried passing the username, the User type, and a!userRecordIdentifier() as the identifier. Here's the code I currently have (and I've verified that ri!username is evaluating to the logged-in user's username).

a!recordActionField(
    actions: {
        a!recordActionItem(
            action: recordType!User.actions.updateContactInformation,
            identifier: a!userRecordIdentifier(users: {ri!username})
        )
    }
)

Any additional ideas for debugging steps would be greatly appreciated. Thank you!

Additional screenshots for context:

The process throws the error when triggered from the a!recordActionField button:

The process starts fine when triggered from the Related Actions tab: