I just came across a bug in the program when using the unsharpen effect.
You can adjust the radius, amount and threshold. Once you moved the threshold slider all and let go of the mouse button all of the sliders become inactive. You can slide them in every direction but nothing will change in the image.
If you hover over the numbers and slide them up and down with the left mouse button pressed the error doesn't occurs. Only if you use the sliders themselves.
Just after resetting the whole effect, moving the sliders will have an effect on the clip again.
I came across this bug when following the steps in this video:
Would be great if there comes a fix for that.