This is a very old issue with some machine controls, I don`t think this is anything to do with BobCAD, I used to have a Bridgeport with a Fanuc 0M control and if I tried to go fast when using softer/easier materials I often got small corners just lopped off, simple solution was turn the feedrate down and all was well again, usually only happened on small say 0.5mm rads with feeds over about 4 metres/min so even with modern controls at very high feed rates it is probably still an issue so try slowing your feeds and see if it helps any
Regards
Rob