Thank you for the rapid reply, Steve.
The camera is a VanTrue R2 dashcam.
I originally started the project with the MOV file on a backup drive. Then I copied the MOV file to the same folder as the Shotcut project file and pointed Shotcut to the new file upon opening the Shotcut project.
I just put the same MOV file into a new project without the PNG file and it is stable. Perhaps the addition of the PNG provided an unstable environment? Perhaps the MLT file got corrupt? Not sure. I am going to leave the PNG out and carry on.
Here are the properties of the MOV file, from Windows and from Shotcut, if they help. (as a new user, I need to provide several replies to include several pictures)
