Any time I use a LUT (on track or individual clip, doesn’t make a difference) using a Crop: Rectangle of any sort distorts the colors that the LUT put in place. If I tweak the coloring so that the LUT looks correct again, removing the crop reverts it back to another (now wrong) color. I cannot figure out why a crop would screw up a LUT’s colors. I have tried both with black padding and transparent padding and it does not make a difference. Tried with multiple LUTs from different sources to no avail.
Shotcut 24.08
Windows 10 Home 22H2 64-bit
Nvidia 3060
Intel i5-9400F
64gb Ram
Operating off a Samsung SSD
There might be something else going on that I did not get from your description. Try to reproduce the problem in a new project and write the steps clearly. For example, what I did for the screenshots above:
Start Shotcut
Double-click a video from Recent to open it
Press A to add the video to the Timeline
Select the timeline clip
Add the LUT filter and choose my LUT
Add the Crop: Rectangle filter and make the rectangle smaller than full size.