(14.0.51.637) TOAD hangs when trying to cancel long running PL/SQL

Run:
exec sys.UTL_RECOMP.RECOMP_PARALLEL( 8);
It runs for a while, so click [Cancel]. All seems OK, till you try to run anything.
Option 1: try to run any query - TOAD freezes (the window goes white/greyed out).
Option 2: click "Terminate" button on the toolbar - TOAD freezes.

The freeze is not infinite. TOAD comes back to the living when the long running task finishes.
But what if you have PL/SQL that runs an infinite loop that you want to terminate?

I see that if I run the EXEC with F5, but it cancels properly if run with F9.

Thanks.