Dr. Awkward said:
The problem is, there's no precedent for single spell effects having multiple durations for their parts. You're not casting entropic shield and pass without trace. You're casting one spell-like ability that duplicates the effects of both spells. It either has a duration of 1 min/level or 1 hour/level or something else, but it probably doesn't have both, just due to the way that duration works. I think that either they meant to specify that invocations with no listed duration have some specific duration, or they meant to specify that multiple effects from a single invocation may have multiple durations. Unfortunately they did neither.