Is this a bug? The preview inside the circle has vanished. Can no longer see the orientation or size. I can still stamp it. But I have to trial and error now to get the right orientation and size because I don't see any preview like before. The "Full Preview Cursor" doesn't do anything either.
I see that when the alpha is removed from the brush and the stamp relies on the grey slider. As a workaround, drag a Polygon 1 into to the Alpha slot for the brush, give it 4 sides and set it to scale 2. With those settings it has no effect on clipping the stamp, but the brush preview is restored.
This issue has been fixed in version 7.2.3, make sure to update.
Confirmed that 7.2.3 works correctly here - thanks Fabrice