The claim that Antioch didn't break communion with Rome until well after 1054 is kind of a moderation of the older claim by Melkite Greek Catholics that Antioch had never officially broken communion with Rome, thus making the Catholic line of succession of the See of Antioch the legitimate one.
I'm unaware of any evidence about Antioch's relationship with Rome in the period between 1054 and the capture of Antioch by the Crusaders in 1097. The Orthodox patriarch of Antioch at that time, John the Oxite does seem to have been willing to cooperate with the Crusaders, but he was exiled to Constantinople in 1100 where he soon died. From then on there were parallel Latin and Orthodox patriarchs of Antioch, the latter living in exile. So certainly, the schism existed in Antioch, if not by 1054, then by 1100.
In 1054, Antioch was under Byzantine rule, and would remain so until 1085. It's very unclear what type of bilateral contacts would've existed with Rome at the time. Though, immediately before 1054 we do have the correspondence of the patriarch of Antioch Peter III with Dominic of Venice. In it, Peter doesn't seem to be as zealously anti-Latin as the other party of the correspondance, Patriarch of Constantinople Michael Keroularios, but he is solidly against Latin practices and is very dismissive both of Papal claims to authority as well as the bishop of Venice's claim to be a patriarch....
Very interesting, thank you.
Do you happen to know about the other churches, and if any of them broke off communion with Rome sometime after the mid-late 11th century period?