Adding a track for a string property through sequence scripting causes the property track to be named "Strings"

Property tracks rely in the default display name for naming in the UI. String tracks have their own override for the default display name getter (UMovieSceneStringTrack::GetDefaultDisplayName) which always returns "Strings". This isn't an issue normally, but when adding the track through scripting the default name is used.

1. Create a blueprint actor and add a string variable to it
2. Check the box for "Expose to Cinematics" in the string's details
3. Compile and save the actor 
4. Add the actor to a new sequence
5. Set up an editor utility widget that adds a key to that variable when a button is pressed (see attached image)
6. Run the widget and click the button
7. Refresh the sequence UI by locking and unlocking it with the padlock icon in the top right.

RESULT

The added track is named "Strings" instead of the variable's actual name