What are some of the recent doctrinal controversial matters in the Eastern Orthodox Church? What are some of the recent doctrinal controversial matters in the Eastern Orthodox Church (say, within the last 10 years), that are yet to be solved? Are there any? Or, perhaps, there are no such ones at all? If not doctrinal, then some matters related to differences in practice would suffice. I heard that Russian Orthodox Church refused to participate in the latest all-Orthodox meeting. Was it due to some of such  differences?
I think the last great doctrinal "controversy" within the Orthodox Church was probably the Council of Florence of 1438-39, which was to have healed the Great Schism between the See of Rome and the other four ancient Sees and the jurisdictions that had grown out of them.  The controversy arose largely over the differences between the eastern and western doctrines on purgatory and the precession of the Holy Spirit, as well over the issue of papal authority.  In the end, the rift could not be resolved and the Orthodox Church remained separate from the west.

The Pan-Orthodox Meeting you refer to was rejected not only by the Russian Orthodox Church (by far the largest Orthodox jurisdiction in the world), but also the Patriarchs of Antioch, Bulgaria, and Georgia - mostly over the wording of some of the pronouncements favored by the Ecumenical Patriarch of Constantinople.  Some of these same pronouncements were condemned within the Patriarchate of Constantinople itself, most notably by some conservative monks at Mt. Athos.  A common theme of those protesting the Council was what was perceived as an erosion of "Orthodox identify and self-understanding" and a dilution of Orthodox theology for the sake of "ecumenism".  One respected hierarch, Metropolitan Hierotheos Vlachos of Greece, for example, protested among other things a reference to Christian traditions outside the Orthodox Church as "Churches" and asked that they instead be referred to as "Christian Confessions".