I have yet another question: in my mappings, I have one scenario, and another entry that is not part of a scenario. It is just supposed to match against the request body content and return a response. The test that is supposed to match against this "not scenario" mapping, is being matched against one of the steps of the scenario. Why? I have a matches that should match one tag of the request exactly in this "not scenario" case.

Hard to be sure without looking at the stubs, but a scenario will always be in one of its states, so if your stub criteria match and the state is correct then the scenario stub will match if it’s first/higher priority than the non-scenario one.