Oecumenius

And concerning the rest of the dead he says they did not live again until the thousand years are completed. He calls dead those who have remained in unbelief, about whom also the Lord said, "let the dead bury their own dead." (Matt. 8:22) Therefore, the unbelievers did not live the spiritual life until the time of the Incarnation is fulfilled, which is the thousand years; for after these things they lived. How? By the visitation and presence of the Holy Spirit. …

Commentary on Revelation ↗

Augustine of Hippo

Anyone who thus participates [in the first resurrection] is one who not only rises from the death of sin but also perseveres in his newfound life. "Over these," says John, "the second death has no power." Therefore, it has power over all the others of whom he said above: "The rest of the dead did not come to life till the thousand years were finished." They may have lived long enough in their bodies, in the period John calls the "thousand years," but they did not rise from the binding death of their ungodliness. …

City of God 20.9 ↗

Bede

The rest of the dead did not come to life until the thousand years were ended. Whoever, during this whole time when the first resurrection, that is, of souls, is happening, has not heard the voice of the Son of God and has passed from death to life, will surely pass, in the second resurrection, which is of the flesh, into the second death, that is, eternal torments, with that very flesh.

Commentary on Revelation ↗