Trick challenge. Any sample you offer (there is no explicit rule) can be immediately reinterpreted as a noun+ noun or noun+ adj string (cf. the pu/Pije ‘pi’ rule), so not a counterexample, despite “obviously” being a prepositional phrase. Thus ‘tan ni la’, ordinarily meaning “because of this, therefore, so” is now “given this cause/reason” with about the same force. It makes very little practical difference, but it does make some explanations harder or more arbitrary (cf ‘pi’ again).