A sudden change in development tempo deprives those assessing progress of a valuable signal. In telemetry we speak of a "loss of signal" event when we can't detect an expected communication. This doesn't mean that the signal isn't there, only that it is not available downstream.
I've been reminded that in human factors a "tempo" can change but to say it has been interrupted is an odd construction. If we are to continue to use the term we should be clear that it is the interpretation of tempo that is interrupted.
Similarly to speak of the absence of a detected signal as an event is from the point of view of the listener. See Apollo 11 Telemetry for the first of many events that almost aborted the landing.
Say more about the line of representation.