Ye Shikai disappeared on the Holy Mountain without a trace. There are only two possibilities: one, he was swallowed whole by the giant beast, and two, he vanished into thin air. From the previous observations of the giant beast, the first possibility has been almost ruled out. The giant beast lounges on the cliff every day, basking in the sun and sleeping, and it seems not to need sustenance, with a temperament... quite gentle. At least in front of the Three Temples members, it has shown no signs of ferocity.
As for the second, vanishing into thin air, this is also the biggest point of suspicion. There are many methods to make someone disappear, time travel being one of them.
Though it sounds far-fetched, aren't cultivators always dealing with bizarre phenomena? At least it's a reason that could explain Ye Shikai's disappearance.
