Bob, I understand. It's tough to cut 'thick' wood.
Everything has to be right, the right blade, the right speed, the right feed rate,
getting up on the right side of the bed,
Have you tried drilling out as much as possible?
One thing I did was to cut a short space then cut a tiny circle to turn the blade 180
and cut back.
You said: ' I'm not sure they can handle the corners '
The corners should be cut last... or cleaned up later.