What is your operating system?
Ubuntu Linux 18.04 (Kubuntu flavor) AMD64
What is your Shotcut version (see Help > About Shotcut)? Is it 32-bit?
Shotcut 201128 linux-x86_64.AppImage
Can you repeat the problem? If so, what are the steps?
If a Preset is added to the Contrast filter with a value above 50%, when the Preset is recalled, an image like this…
Also, after recalling the filter, when the time is advanced by as little as one frame, the indicated value jumps from the preset value to “100%”, although the image display is not the same as appears when 100% contrast is set manually.
Other filters , and their presets, function normally.
Presets for Contrast appear to function properly if the value is less than 50%
A demo video is available.