Napoli Centrale Trains July 27 - 30

I am looking to book a train from Florence to Naples on July 27. I found it odd that neither Italo or Trenitalia had any opitions. Then I looked at July 28, 29 and 30. All show no results. But readily available for July 26 and July 31. Is this a stike or closure? A closure for 3 days in the middle of the summer seems odd. Any ideas what this could be? Even the Rome to Naples schedule looks limited those dates