You are unable to change the filepath for Datasmith Scenes. The '...' box is there for you to select but it does nothing when clicked.
This issue happens in both 4.19.2 (0.182) and 4.20.1 (4.20E2)
Results: Window doesn't open to change the file-path
Expected: Window opens and the file-path of the scene can be changed.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-63097 in the post.