one CPU thread being used despite having 6

I have a Mac Pro (late 2013) with 6 core processor, 32GB RAM. I have created an aggregate device in Audio Midi setup for my Apogee Ensemble Thunderbolt and an older MOTU Traveler. This is necessary because the Eventide H7600 I want to send to only has an AES digital I/O, which won't work with the Apogee, but the MOTU has this particular plug in back. I am running logic with a project that has ONLY a stereo guitar recording. The track has the Linear Phase EQ on it, and it is sending to the Eventide H7600 via the I/O plug in using the digital in/outs. The return signal is being processed by iZotope's Ozone 6 on the final output track.

When I select different presents in Ozone, the CPU maxes out, producing clicks. When I bring up the CPU/HD window, it shows only one core being used. In Audio Prefs, the "thread usage" is set to automatic. Setting it to 6 and applying the changes does nothing. Still only using one CPU.

Never experienced this with Digital Performer, which I am trying to resist upgrading and transitioning totally to Logic. This isn't helping!

Any idea what is going on here? Anyone else noticing this?