Using the Bezier Masking effect, I find that while the white control nodes on the corners of a rectangular mask work as expected to resize the mask about its centre, the yellow control nodes in the middle of the sides are dead - I do not get a 'stretchy arrow' cursor, and they do not allow control of width/height.
The Width and Height sliders in the effect details box do work, but this is inconvenient.
I have the same problem with VP21 on two PCs, each with a different make of video card (nvidia and AMD), so I can't think that is relevant.
All video tutorials and the built-in help indicate that the yellow control points should be operational.
Am I missing some setting somewhere?
I would be glad of any suggestions!