I would think that form action should  work unless there might be an issue with a searchable user field or the user not available in the list.  Is the user selectable in the field without the form action?

There is a couple of ways without an appscript. You could set the default in Web Admin for the transition:

If it is a searchable field, you could maybe make non-searchable (if possible) or you could select to create a form action "Execute Javascript" and do the following, as it forces the search on the field:

SetFieldValue("Data Entry Specialist", \{'id':{_UserId}, 'name':'{_UserName}')

MichaelCFiala  Thanks for the reply! Can I know where can I find that screenshot in the admin portal please? and where can I find such that javascript examples? I didn't find it the sbms_js_library.pdf documentation

For setting user defaults, you can also set them at the workflow in the Application Administrator.

"Application Administrator > Workflows > [Your Workflow] > States/Transitions > [Your Transition]  Details > Fields > [Data Entry Specialist] Details > Set Allow Override & Set to Value to Default Value > Manage Group Users Default"

For setting user defaults, you can also set them at the workflow in the Application Administrator.

"Application Administrator > Workflows > [Your Workflow] > States/Transitions > [Your Transition]  Details > Fields > [Data Entry Specialist] Details > Set Allow Override & Set to Value to Default Value > Manage Group Users Default"