This is because the onValueChanged function checks if the slider has a different value from the settings and updates the settings if it does. The slider has a max value of 100, so when setting the sliders value to 1000 the slider would update to have a value of 100. This would then update the setting to value to 100.
The fix is as follows. When updating the slider value > 100 just ignore the first onValueChanged. Following onValueChanged, which are triggered by the user sliding the slider, will still trigger.
CURA-9488
fd8d6498ee