Trying to figure out what could be off with my Moogerfooger connections to my Voyager RME

I just bought a Moogerfooger 12-stage phaser on Reverb. It didn’t come with a power supply so I got the specs, (9vdc minimum 200ma Centerpin positive) and found a 9v cord on Amazon that seemed like it could work.

Then I tried to patch it into the Voyager as an effects loop as layed out in the manual, tip- in effect, ring out from effect to TRS into Mix/Out Loop jack of the Voyager.

The audio was cut dramatically, although I could hear the phaser working faintly in the background. Raising the output level of the phaser didn’t seem to bring the signal anywhere listenable either.

I also tried it straight stomp pedal style, straight in line, same result.

And I tried it as an insert in a mixing board, same result.

Is it an impedance issue? Maybe incorrect voltage from the random 3rd party Amazon vendor’s 9v cord? None of the above?

It seems like I must have something mismatched somehow. Any ideas? It’s probably something obvious, but I’m musician and absolutely not a tech!