The Greek uses the prepositional/conjunctional phrase
"until" or
"till" the thousand years were completed. Not
"by" the end of the 1000 years or "prophetic" day.
Rev 20:5 οι G3588 δε G1161[BUT THE] λοιποι G3062[REST] των G3588[OF THE] νεκρων G3498[DEAD] ουκ G3756[NOT] ανεζησαν G326(5656)[LIVED AGAIN] εως
G2193[TILL] τελεσθη G5055(5686)
[MAY HAVE COMPLETED] τα G3588
[THE] χιλια G5507
[THOUSAND] ετη G2094
[YEARS.] αυτη G3778[THIS "IS"] η G3588[THE] αναστασις G386[RESURRECTION] η G3588[THE] πρωτη G4413[FIRST.]
I can see why