did you cut some relief behind the cutting edge of the reamer? i know i made that mistake, the relief was not enough and it was not cutting just rubbing the inside of the die... if you did it right you pull out the reamer and a pile of fine metal cuttings will be on top of the blade, not all along the blade but mostly near the tip section...
did you drill out the eject punch hole? the tip of the reamer will use this hole to center/feed itself....
i snapped several reamers, easy does it, literally millimeter by millimeter and pull it out often to clean out the cuttings... once the reamer 'grabs' and digs into the metal its all over...
maybe try some O1, i had some good success with it...
you aren't a swaging die maker until you snap a reamer! keep at it, you are educating yourself on how to get this done and what it feels like on the lathe... when i get frustrated with the dies i just walk away and do something else and pick it up again the next day, gives me time to think thru problems and get the enthusiasm back...