Finally, I got it to work with sequencer and it’s very easy! I found this page:
I used a sequence for the door animation using sequencer instead of using matinee. The blueprint is very simple as shown in the attached image. The trick is to add a shot track in sequencer, then right click any tracks in matinee main window and choose >>> properties >>> when finished “keep state”. See the second attached image.
Now I think I can ditch matinee for good! You know what? Matinee is a pain in the A$$$, sequencer is much easier!