Screenshot -capture selected portion - broken
In MacOS Catalina, When I try to use Screenshot the Capture Selected Portion option, the screen darkens except for a default selection. But I am unable to change the size and location of this selection. When my mouse is over one of the handles, the cursor changes to a drag-like cursor, but clicking and dragging on any handle does nothing. Nor can I move the selection overall using the grab cursor that appears. Is there something I am missing?
I'm familiar with the work around command-shift-4, but this product (which was working for weeks) is broken now. How can you reinstall it, or get this fixed?
Mac mini, macOS 10.15