Hi,
agreed if summation[11](S1<S1[1])<=10 is on its own, then it doesn’t say where is at least one missing occurrence, my bullet point (2.) above says the same thing.
When I combine it with “summation[5](S1<S1[1])=5 AND …”, then to have C1 true we need both summation subconditions to be true, and for this summation[5] subcondition to be true, it means none is missing in the latest 5 occurrences, so when C1 is true, both subconditions are true, necessarily the missing occurrence is between 6th and 11th. If it was in the latest 5, then the summation[5] subcondition would be false and C1 false with it.