RR NDB
1) Is the power being applied to the AS probes enough in order to their proper operation?
2) The delay between a sudden atmospheric temperature drop and the "reheating" of the probes could explain the "failures" leading to UAS?
3) The differences between US and FR probes may be explained by "different" time constants?
4) Is the max power sufficient to provide a safe operation in most environments?
good start but to better understand what questions are applicable first search on High altitude "ice crystals" in aviation
I suspect that you may better understand the time differentials between sensing and applying enough heat.
Note that you car windscreen will still ice up and then shed while the defroster is on high, as the sleet density vs your speed changes rapidly.