If anybody has an issue with this in the future I finally found the root cause! So I must not have fully understood how Spandex worked. What ended up happening was the GenServer process never fully closed a different trace so my private API call was on a different trace than my public API call.
I was able to diagnose that by logging out the trace_id on both sides of the GenServer.call/3 and making tweaks until I could get them both to be the same. Works like a charm now!
