Your sum(total Output) should always return a value if sum(Output) does. It does not seem to work in your first screen shot. Could you please recheck that the field names are correct and that you don't mixed up field names and expression label names by accident?
In your OEE weighted, I think you're having problems with the implicit DISTINCT qualifier of the aggr() function, you could try to add NODISTINCT qualifier to the aggr() function, but not sure if this will get you correct results.
I would need to go somewhat deeper into the expressions (they are indeed a little bit complex), if you could post some small sample, that would make things much easier.