>>854646
OP here. Chalcedonian Orthodox are our brothers and sister in Christ, fully Orthodox of course, separated only by our communions. As for Roman Catholics, we accept their baptisms as legitimate, and see them as a legit communion, but otherwise they are considered heterodox. Protestants too are considered heterodox, and we do not accept their baptisms.
>>854648
Honestly, mainly just canonical issues. For example, the reinstatement of Nestorian theologians like Ibas of Edessa at Chalcedon which we believe contradicts the decision at Ephesus, as Ibas was a clear Nestorian. There are other canonical issues I won't get into as well. Chalcedon may be Orthodox in doctrine, but for its canonical issues we cannot accept it. If the Eastern Orthodox did not make us have to accept Chalcedon as Ecumenical, then we'd happily be in full communion with them.