Apparently all Class 700 units in the affected area (I'm currently near St Neots) have come to a stand because a power blip has occurred, and it's affecting only this type of train. All other train types are unaffected. I'm currently on 9J44 near St Neots. Fortunately it looks like most, if not all, of the affected trains are not affecting junctions, so other trains can bypass them. My train is currently being reset multiple times in an attempt to resolve the issue, but no luck so far.