More often than not ALT+x does not work as intended or does not work at all. When it does work: after I try to remove mark placed earlier, the "inner circle" still stays. Forever. When it does not work.. well, it does not work. Error messages can be seen in screenshot I attach.
alt+x does not work
If this is still happening with 4.3, please update the bug and attach the file Logs/PythonErr.log and PythonDbg.log.