On September 16, The Hollywood Reporter confirmed that Cruise's dispute with the studio had been resolved, and production would now begin in spring 2017. In November (2016), Jeremy Renner—who portrayed William Brandt in the fourth and fifth films—stated that he was unsure if he would be part of the sixth film, due to scheduling conflicts with Marvel Studios' Avengers: Endgame
The films were originally scheduled to be shot concurrently, with the Russos suggesting that "some days we'll be shooting the first movie and some days we'll be shooting the second movie. Just jumping back and forth." Anthony Russo felt it made more sense to shoot the films simultaneously, due to financial and logistical reasons, considering the large number of cast members, even though each part is its own distinct film.
At the end of April 2015, Evans revealed that filming was scheduled to start in late 2016 and take place over nine months, lasting until August or September 2017.
In January 2016, the Russos stated that filming would take place in Atlanta, Georgia, beginning in November 2016 and lasting until June 2017. In October, Feige stated that filming would begin in January 2017.
Renner, Olsen, and Bautista noted that the actors appearing in the films had not received scripts before the start of shooting, with Bautista specifically stating on January 22, 2017, that he had not received a script, despite beginning his filming on January 23. No actor in Infinity War had the entire script, though some who were in the film had access to more scenes than others. Additionally, fake and redacted scenes were used to help protect the secrecy surrounding the film.
In April 2017, Feige revealed that the sequels were no longer being filmed simultaneously as originally planned, but rather back-to-back, and indicated that filming for the Infinity War sequel would commence in August 2017. He explained, "We're doing them one right after another. It became too complicated to cross-board them like that, and we found ourselves—again, something would always pay the price. We wanted to be able to focus and shoot one movie and then focus and shoot another movie." As this decision was made a few months before the start of filming, some of the pre-production work was negatively affected. Some scenes from both films did ultimately get shot on the same day, mainly to accommodate actor availability
So basically Renner was committed to both Infinity War and Endgame at the time of MIF since the plan was to film both MCU movies at the same time so he wasn't available.