What is your operating system?
Windows 10 20H2
What is your Shotcut version (see Help > About Shotcut)? Is it 32-bit?
Can you repeat the problem? If so, what are the steps?
New (empty) project. Drag / drop a clip into SC. If the color range is wrong, set the clip’s color range to Full. Source player is not updating (i.e. the material is outside the 16-234 range, even though you’ve forced otherwise).
If you drop the clip onto the timeline, it shows correctly in the project player.
But flip back to the source player, and it’s still wrong.
Project seems to export with the right color range. I round-tripped an export back in to SC.