Audiobus: Use your music apps together.
What is Audiobus? — Audiobus is an award-winning music app for iPhone and iPad which lets you use your other music apps together. Chain effects on your favourite synth, run the output of apps or Audio Units into an app like GarageBand or Loopy, or select a different audio interface output for each app. Route MIDI between apps — drive a synth from a MIDI sequencer, or add an arpeggiator to your MIDI keyboard — or sync with your external MIDI gear. And control your entire setup from a MIDI controller.
Download on the App StoreAudiobus is the app that makes the rest of your setup better.
How to get Blocs Wave to work in AUM
Just start Blocs Wave first and then load it into AUM.
This solves the problem of Blocs connecting directly to system output, and gets it to properly route to AUM track input. @AmpifyxNovation know of this bug and are working to solve it, so try this in the meantime.
This method was posted in another thread previously by another member whom I cannot recall, so credit goes to that unknown member. Thanks to them for originally posting about it. 
Comments
Seems to be fixed on last update. If still not working try un/re install, but back up your projects first.