The issue should come up after adding a SP&R filter, did you change the zoom, thats what I used in my original edit and this video as well, once that is done the outline appears, if I reset all in SP&R filter then outline disappears.
I am using Shotcut version 25.05.11, this is because I have issue with the newer ones as shared by me in the following post.
I will try once with newer version to see if the problem is due to that or not, will share the result once I test it.
Thank you again for your time and reply.