Windows 11
Shotcut version 23.09.29
Exporting an image spanning multiple frames with full color range in the yuv444p pixel format (and yuv420p10le and possible more) only creates proper (true to original image) color for the first frame. Every subsequent frame looks like a full color image being read as limited (slightly darker).
To reproduce:
In video, set color range to full. In other, add pix_fmt=yuv444p. Rest of settings are unchanged from the default preset. Every image object lasts for 3 frames in this instance. I am a new user, so I can only post one media item unfortunately, but to describe the result, the first frame of every image object will be true to the orginal image in color, and the following two will be slightly darker.
The same process, but changing the pix_fmt to yuv422p, or making every image object only last one frame, creates a video true to the original image. Yuv420p (the default) does not seem to be able to create any full color frames true to the original, but since the same behavior persists using ffmpeg, I assume thats a limitation of the format.