Yes, brother vooks, we as Seventh-day Adventists fully understand this text, and the entering into "the holy place" "once".
Jesus indeed entered once for all, but into
Where, according to the text specifically in Hebrews 9:12?
It was into the Sanctuary, the Holy place, through the First veil alone, not through the Second then:
Neither by the blood of goats and calves, but by his own blood he entered in once into the holy place, having obtained eternal redemption for us. Hebrews 9:12
See Hebrews 9:2-3:
For there was a tabernacle made; the first, wherein was the candlestick, and the table, and the shewbread; which is called the sanctuary. Hebrews 9:2
And after the second veil, the tabernacle which is called the Holiest of all; Hebrews 9:3
Paul is clear about the typology, First comes the First {part of the} Tabernacle, wherein was the Candlestick and the Table, even along with the Altar of Incense:
Now when these things were thus ordained, the priests went always into the first tabernacle, accomplishing the service of God. Hebrews 9:6
Where is Jesus standing in Acts 7 {part of the Church of Ephesus} and where is He seen walking in Revelation 2:1?
Unto the angel of the church of Ephesus write; These things saith he that holdeth the seven stars in his right hand, who walketh in the midst of the seven golden candlesticks; Revelation 2:1
Which of the two compartments of the Tented Sanctuary is that?
It is verily the First,
not the Second.
Hebrews 9:12 {as also vs 24 "agia" and vs 25, "ta agia"} simply reads ta agia, which is the Sanctuary, and
not agia agion, the Holy of Holies.
Nor yet that he should offer himself often, as the high priest entereth into the holy place every year with blood of others; Hebrews 9:25
Paul is very clear about the separation of the two veils. It never says Jesus entered through the Second Veil, and did not then need to at His 2nd Ascension, being from the Mt of Olives. We see Jesus ascending in Psalms 24 and compare Revelation 4 and 5 {compare to Acts 1-2 and Psalms 133; Exodus 29:7; Leviticus 8:12; there also needed to be 12 - Exodus 28:21-22, 29:5, 39:14, then the Holy Spirit was sent – Revelation 5:6}. Revelation 4 speaks of the First Veil:
After this I looked, and, behold, a door was opened in heaven: and the first voice which I heard was as it were of a trumpet talking with me; which said, Come up hither, and I will shew thee things which must be hereafter. Revelation 4:1
Thus John is taken in the Holy Place, the First 'Tabernacle' of Heaven, revealing the 7 lamps which sat directly across from {before} the Table of Shewbread which was Crowned, and had two stacks, representing the Throne of God in the Holy Place:
And out of the throne proceeded lightnings and thunderings and voices: and there were seven lamps of fire burning before the throne, which are the seven Spirits of God. Revelation 4:5
Revelation 3:8, in the
period of the 6th Church, thousand{s} of years {1800+ yrs} later from the First Church of Ephesus, another door/veil is seen opened in Heaven, while the first was closed, and this is also witnessed in Daniel:
And to the angel of the church in Philadelphia write; These things saith he that is holy, he that is true, he that hath the key of David, he that openeth, and no man shutteth; and shutteth, and no man openeth; Revelation 3:7
I know thy works: behold, I have set before thee an open door, and no man can shut it: for thou hast a little strength, and hast kept my word, and hast not denied my name. Revelation 3:8
I saw in the night visions, and, behold, one like the Son of man came with the clouds of heaven, and came to the Ancient of days, and they brought him near before him. Daniel 7:13
Jesus was presented once as the Sacrifice [Calvary], once for all {Revelation 5:6, notice past tense "as it had been slain"}.
If you mean that Jesus was not again brought into the presence of the Father since His Ascension from the Mt of Olives, that would be incorrect, since Jesus and the Father moved from the Holy Place in the Heavenly into the Most Holy Place in 1844 {Dan 8:14 &c, and then Thrones being "set" in both Daniel and Revelation}, and the Father went first, the Son coming after as is apparent from Dan and Rev.
Jesus
didn't stand in the Holy of Holies in the Heavenly in the first Church age of Ephesus, but rather began to do so in the 6th Church Age of Philadelphia.
Jesus will also move again back into the Holy Place, not as Mediator, that door will have been shut forever {Luke 13:25; Daniel 12:1 &c}, but coming as King of Kings, before coming out unto this earth, Hebrews 9:28 and Leviticus 16, even as 2 Kings 11:11-12.
It is quite apparent from Revelation 20 that the Scapegoat portion of Leviticus 16 & 23 is still yet to take place.