A locked attachment can be deleted on the New User Experience (UX) grid
Expected Results: The Delete is not there and cannot be deleted like it is in the Classic UI
Actual Results: The document is deleted
Release : 16.0.0 and higher
This is working as designed.
When the 'Documents' module was introduced to Projects, the goal was to streamline and simplify user access to documents. The decision was made to NOT bring forward the Classic document management capabilities to the MUX.