What is your operating system?
Windows 10 64-bit
What is your Shotcut version (see Help > About Shotcut)? Is it 32-bit?
Can you repeat the problem? If so, what are the steps?
Set “Preview Scaling” to 360p
add a video file
add an “Old Film:Projector” filter to the video,
set “Vertical Amount” to “1”,
Only seems to happen with 360p preview scaling, 540p and 720p work fine.
Proxies are turned off.