Inside mged in the command window I execute:
mged> B all
# two overlapping regions appear
# no response
The overlaps tool seems to work ok, and the outside command line version of rtcheck works. I'm using BRL-CAD version 7.20.2.
That bug was noticed shortly after release and affects all of the rt* commands (even 'rt'). The trace actually runs, but the output ends up inadvertently getting suppressed. It doesn't write to the text console window so you don't get any feedback that it ran and completed. I suspect if you rotate the model, you'll even see the yellow overlap lines even through you didn't see any text output.
I put a release note in to make sure before 7.20.4 goes out, but this bug should already be fixed. Thanks for taking the time to report it though.