The new episode of the MJCast podcast details the production issues the movie has been having. Basically, Lionsgate got spooked when the Cascios threatened to accuse MJ of abuse late last year.
Lionsgate are concerned that new allegations will hurt the success of the film. This, according to the MJCast, is why many of the scenes involving the Chandler case are being reshot and the movie rewritten. This (again, according to them) is the real reaspn the movie has been delayed until October. They are also doubtful the movie will come out this year at all.
You can listen to the episode here (around the 26 minute mark):
https://podcasts.apple.com/us/podcast/175-ten-years-on-and-goin-strong/id965404693?i=1000698467207