This is strange, I have run into this exact same problem today. Super mirror black (from another company) will not flow out smooth for the life of me. Mine is on some aluminum motorycle case covers. I was also having a slight outgassing problem (only noticible when you examined the parts real close.)
Like you, it's got me stumped. Tried different temps, outgassing, scotchbrite then recoating (which had worse appearence than 1st coat
)
I look forward to hearing some suggestions.
Greg