Filtering seems to be subtly broken

Summary: See the list under Critical in this Space for the model -- it's showing lots of Issues that it shouldn't be.

The problem is very subtle. Extensive testing suggests that, if the pipeline filters out everything, leaving the results empty, and that empty list gets fed into a Property on the target type, and that target type is not defined on the lexical context (that is, I'm showing this from the Space, not from the type's Model), then the last filter stage that produced the empty list gets ignored.