2012 Mac mini doesn't need 1.35V RAM. How do I know? Cause I'm running 1.5V RAM in my 2012 mini no issues. For Haswell-based systems, depending on the system it might not boot with 1.5V RAM (my Intel NUC Haswell-based system won't even post without 1.35V RAM, but my Haswell 2014 5K iMac is using 1.5V RAM without issues).
Anyway, that memory may just be slightly incompatible. I'd send it back and get some Crucial or Corsair - try something different.