The third time was not the charm for Janet Jackson, who announced her split from husband No. 3, Wissam Al Mana, in early April. What went wrong so soon after the birth of their son, Eissa, on Jan. 3? “There were numerous problems,” an insider says, “but the main one was that Wissam didn’t want Janet going on tour. He doesn’t like his wife living in the public spotlight, even though that’s a big part of who she is.” Janet, 50, and Wissam, 42, remain on good terms, the insider says, and plan to co-parent Eissa in harmony. “They really tried to make it work,” the insider adds of the five-year marriage, “but the differences were just too much to overcome.”…