Were there any early Christians who defended non-procreative sex as licit?
Having read through quite a bit of the Ante-Nicene Church Fathers, I can't remember ever seeing anyone advocate for non-procreative sex. Rather it was common to advocate for remaining a virgin for life.
I think if anyone in the early church did advocate for non-procreative sex, you are more likely to find them among those whom the Church Fathers debated against and labeled as heretics.
Keep in mind, also, that they didn't have condoms back then or the concept of "safe sex." And there most certainly weren't any church fathers advocating for homosexuality - which would contradict the scriptures (and the early church fathers drew heavily from the scriptures).
Of course, "early Christians" in a broad sense could include fringe sects embracing all manner of licentiousness (e.g., Carpocratian orgies). If we limit the scope to the Church Fathers:
It would depend somewhat on what you mean by non-procreative—deliberately contracepted, performed in a manner incompatible with procreation (i.e., sodomy), undertaken in the absence of fertility (e.g., post-menopause), undertaken without any intention of procreation, or undertaken without procreation as the sole purpose, to distinguish several cases.
Anyway, a pertinent example is John Chrysostom, who (with the implicit equation of licit sex with marriage) writes in his Homily on Marriage 1 (late 4th century):
These are the two purposes for which marriage was instituted: to make us chaste, and to make us parents. Of these two, the reason of chastity takes precedence. When desire began, then marriage also began. It sets a limit to desire by teaching us to keep to one wife. Marriage does not always lead to procreation, although there is the word of God which says, "Be fruitful and multiply, and fill the earth". We have as witnesses all those who are married but are childless. So the purpose of chastity takes precedence, especially now, when the whole world is filled with our kind.