Though we knew it played a role in director Gary Ross’ decision, a new article from The Hollywood Reporter indicates it was all because of Jennifer Lawrence’s X-Men shooting schedule.

Fox had set a January start for the First Class sequel, which means that Catching Fire filming had to be complete by the end of this year. That was too little time for Ross, reports THR:

Ross did not allude to Fox, which had imposed that schedule by putting a January start date on its X-Men: First Class sequel with an ensemble role for star Jennifer Lawrence. And Ross did not express his misgivings about the particular challenges that he perceives in framing and executing a film version of the second book, Catching Fire.

Fox’s January date led the bond company on Catching Fire to insist that Lionsgate commit to finish filming by Dec. 20, backing the studio into a production schedule with an August start date that Ross felt he could not accommodate. (Fox’s deal with Lawrence predates her contract for Hunger Games, putting X-Men in a priority position.)

According to knowledgeable sources, Lionsgate Motion Picture Group co-chair Rob Friedman pressed Fox to set a later start date for the X-Men movie, even offering allurements such as a chance to handle some of the overseas distribution on Catching Fire.

Fox was willing to move its start date back a few weeks and is still in conversations with Lionsgate on that issue. But the additional time would not have been enough to allay Ross’s concerns. And Fox may have been inclined to cooperate only up to a point. When the first X-Men film was released in June 2011, the studio very much wanted Lawrence to attend the premiere. The star was starting The Hunger Games then and Lionsgate did not make her available, apparently causing severe friction with Fox. Friedman, who was not at Lionsgate then and has a good relationship with Fox’s Tom Rothman, has been negotiating to win a little more time. Lionsgate is now said to be confident that it can complete shooting in the time allotted.

It’s a shame that Ross’ involvement came down to Lawrence’s schedule, but that’s just the business, we suppose! We wonder if she feels at all bad about it coming down to her filming conflict.