you are correct that this may be your problem. It is tripping out and then the spindle drive releases control of the spindle and it coasts to a stop using friction to stop it instead of a energy dumping resistor. Has it functioned correctly before? Is it possible the resistor is open (no resistance)? I do not have a set of TC22 parameters with me for the spindle drive. Someone on the forum with such a machine can look up the value for you. You may have to provide the parameter number.
George
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)