Problems with rotation, light to dark mode and vary with traits

[sundialsoft]

I found that I could not vary with traits in IB to adjust the size of the slider for different devices and orientations. The slider seems to lose something and internally gets a NaN.
Similarly when changing light to dark and dark to light modes the slider loses the place.
In both cases the volumes went to the middle of the range and resetting the slider caused a crash.

So there is something happening which can easily be seen just by changing dark mode to light.