Follow up:  As it turns out, it was my younger brother (3,000 miles from here) that was "mucking about" with the camera using browser access.  It was he who had created the black rectangles and told me that since they couldn't be seen in subsequent screen shots, he thought that he had done no harm.  I find it strange that a browser can paint in those areas and that the dedicated application can't remove them without a restore. Even a re-boot didn't work. 
  
More importantly... where did you say you put the beer?
  
Peter
 
 

CORRECTION: The "black squares" DID show up on all computers including Android Tablets.
FIXED: The problem was in the camera. The cure was Device > System > Maintenance > Restore.

I would have posted earlier but ...
Hi Joseph... Thanks for trying to help.
Peter

After updating to v8.16.10, previously selected areas of "Non-Detection" have gone from grey to black and can NOT be "erased" or "cleared".
This is happening on only one of four computers.  I have revo-uninstalled the application and re-installed it but the results are the same.
Can anyone suggest a fix?
Thanks for stopping by.
Peter (Win'10)

Audio from the internal microphone of my RLC-510A sounds like someone at the bottom of a large barrel with a mouth full of marbles as heard on a badly tuned single side-band receiver.  Also, it appears no effort was made to reduce wind noise.  Have any of you tried to bypass the mic by adding an external one.  If so, could you please let me know what type you used (ie: typical phantom powered computer mic, dynamic mic, etc) and any problems that you encountered.
 
Thank you very much.
Peter
Windows 10, Reokink v8.15.7