I'd bet it's the voltage.
the mr33 needs at least 37V
You're powering your hEX PoE with 12V. AFAIR there's no up-stepping. Power your device with at least 37 Volts and it should work.
And from my experience with the mr33, better go with 48V directly (they can be divas when running at the lower end of the supported voltage range).
MTCNA, MTCUME, MTCWE
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