There is no conflict. The perception of conflict is of man's misunderstanding.
The "salvation" of Hebrews 1:14 is the Greek "soteria" which means deliverance, or salvation. (1) The English translations are reading a belief system into the scriptures, failing to recognize the deliverance that was coming to the newly birthed "church" of the first century AD. The CJB translates this verse best.
"Aren’t they all merely spirits who serve, sent out to help those whom God will deliver?" (Heb. 1:14, CJB)
And there is the element of time which Young's notices.
are they not all spirits of service -- for ministration being sent forth because of those about to inherit salvation? (Heb. 1:14, YLT)
As the Hebrews who received this letter were believers in Christ, who had converted to The Way, the availability of their heavenly salvation had been established at the cross in AD 30-31. So the "salvation" or "deliverance" in Heb. 1:14 had to be another deliverance they were waiting for, which was about to be provided for them.
"28 so also the Messiah, having been offered once to bear the sins of many,[c] will appear a second time, not to deal with sin, but to deliver those who are eagerly waiting for him." (Heb. 9:28, CJB)
"28 so Christ, having been offered once to bear the sins of many, will appear a second time, not to deal with sin but to save those who are eagerly waiting for him." (Heb. 9:28, RSV)
The second appearance of the Messiah was promised to that same generation of the first century AD who had seen His first appearance. The first appearance / manifestation was for deliverance from sin, which He accomplished at His death on the cross and subsequent resurrection from the grave.
The second appearance then was not for the purpose of heavenly salvation, not for putting away sin, but for a different deliverance. Those new converts to The Way, those newly born of the water and the spirit (John 3:5) were still suffering under the constant push from the Judaistic teachers to come back under the law of the temple worship system of animal sacrifices. All of Hebrews discussed the better sacrifice of the blood of Christ which is now the only blood sacrifice that God now accepts for forgiveness of sins (Heb. 9:13-14; 10:4).
They were also being persecuted by the Romans as Nero had blamed them for the fire which engulfed Rome in AD 64. "..they were covered with the hides of wild beasts, and worried to death by dogs, or nailed to crosses, or set fire to, and when the day waned, burned to serve for the evening lights." (3)
The letter to the Hebrews was written approx. 60-65 AD, no later than AD 66. (2) It predates the destruction of Jerusalem and the temple. All of Matt. ch. 24 & 25 warned the disciples of the signs they were to watch for and to be ready before the destruction of the temple would take place. He told them to watch for the armies that would surround Jerusalem (Luke 21:20-21), and then to flee to the mountains.
Those who believed Him fled Jerusalem when they saw the Roman armies. They got out of the way before the Roman-Jewish wars began in AD 67, and were delivered, or "saved" from that destruction. Those who believed fled to the mountains in Pella. When the temple was destroyed the animal sacrifices at that temple ceased, and the power of the Sanhedrin was destroyed. They could no longer torment and torture those who fell into their hands and refused to deny the Messiah.
The deliverance of Heb 1:14 was their fleshly deliverance from persecution of both the Jews and the Romans of the first century AD. Not for sin, but for the establishment of the kingdom so that the gospel of Christ spread from Jerusalem out to the rest of the world.
See my post "Which Salvation Arrived in AD 70...." at ShreddingTheVeil
Time matters. The first audience perspective matters. We have to stay in context and understand the scriptures from their perspective.
Further reading - "Crossing Over" at ShreddingTheVeil
1) Strong's Gr 4991 - soteria Biblehub
2) Date of the Letter to the Hebrews DatingTheNewTestament
3) Nero Persecutes the Christians EyewitnesstoHistory