My neon pink turned muddy brown on a 200-shirt order in Austin
Overprint the pink with a light pass of magenta at 20% before the final layer, fixed it in one test run, anyone else fighting dirty yellows and pinks on poly blends?
...so yeah I had the same thing happen with a run of hot pink hoodies last fall and it drove me NUTS. That muddy brown is usually the poly base fighting the pink dye. What worked for me was flashing the shirt with a quick low temp cure before laying down the pink at all, then going back with the magenta boost like you said. Also check your mesh count, I was using a 156 and dropping to a 230 made the pink sit on top way better instead of sinking into the fibers. And watch your dryer temp on those blends, anything over 320 and the pink shifts fast. The 20% magenta trick is solid, I now do that as a standard underbase for any pink on polyester. Good luck with the reprint, that's a rough one to eat on 200 units.