According to this report from Channel 4's Football Italia, at least three grounds are still not ready to operate at full capacity:
[T]he Stadio Friuli in Udine and Catania’s Stadio San Filippo have still not passed checks. Work is ongoing to install the turnstiles, so Udinese and Catania have been allowed to play their first game of the season away from home to enable it to be completed quickly. The Stadio San Paolo in Naples is also an issue, so the third tier has been ruled off limits and the capacity reduced to 75,000.Maybe my colleague BL is right: though a continent away, Italian soccer is a lot closer to Latin America than it is to Western Europe.
San Siro increases capacity [Channel 4]
Italian league halted by violence [BBC]