(1) - Proclus believed the story to be true, in his Timaeus commentary he also recorded the opinions of other people:
He wrote a commentary on the Timaeus, now lost, but his views were again recorded by Proclus.
It is true that some ancient authors, mentioned by Proclus for example, were skeptical of the story, as we are about to see, and Renaissance and Enlightenment writers probably projected this skepticism onto Aristotle, since he was already seen as Plato’s intellectual “critic”, however scholars today generally agree: there’s no direct evidence Aristotle said anything about Atlantis. It's a ghost reference born in the 18th–19th centuries.
There were actual ancient philosophers, Neoplatonists even, who considered the story of Atlantis a metaphor or allegory of "the natures that are perpetual or are generated in the world", "images of the oppositions that pre-exist and exist in the cosmos" etc, but Proclus reminds them how Plato has always affirmed the veracity of the story: "the narrative is surprising in the extreme, but it is true in every respect", "and if it is true in every respect it cannot be true only in part or in appearance or only in its symbolic meaning".
Apparently, they failed to notice that many authors of classical literature, such as Proclus, Diodorus, Plutarch, Posidonius, Strabo, and Pliny, all made references to Atlantis.
Proclus, a prominent 5th-century Neoplatonist philosopher, referenced seven islands sacred to Persephone in his commentary on Plato’s Timaeus.
Proclus, in his commentary on Plato's Timaeus, cites Marcellus' now-lost work Aethiopica (or Ethiopic History) to support the existence of Atlantis.
Supporting excerpt from Proclus' commentary (as preserved and quoted in secondary sources):
A scholia quoted from Proclus by Humboldt and Boeckh says: ‘The historians who speak of the islands of the exterior sea tell us that in their time there were seven islands consecrated, to Proserpine, and three others of immense extent, of which the first was consecrated to Pluto, the second to Ammon, and the third to Neptune. The inhabitants of the latter had preserved a recollection (transmitted to them by their ancestors) of the island of Atlantis, which was extremely large, and for a long time held sway over all the islands of the Atlantic Ocean.
Proclus was a Neoplatonist philosopher who commented on Plato's works, including the Atlantis myth.
In the lesser Panathenæ they carried another peplum (covered with symbolic devices), which showed how the Athenians, supported by Minerva, had the advantage in the war with the Atlantes.' A scholia quoted from Proclus by Humboldt and Boeckh says: 'The historians who speak of the islands of the exterior sea
Proclus quotes an extract from an ancient writer who refers to the islands in the sea beyond the Pillars of Hercules (Straits of Gibraltar), and says that the inhabitants of one of these islands had a tradition from their ancestors of an extremely large island called Atlantis, which for a long time ruled over all the islands of the Atlantic Ocean.
According, to Herodotus, they were introduced by the Hyksos; and Proclus, the Platonic philosopher, connects them with the science of astronomy--a science which, he adds, the Egyptians derived from the Chaldeans.