How does the cleric's Destroy Undead feature interact with undead above its CR threshold?

Question

Just to make sure this is all RAW:

A level 5 Cleric uses their one use of Channel Divinity to use the Turn Undead effect. The zombies in the area that fail the save are instantly destroyed; the zombies that passed the save are now turned and will move as far away as possible during their turn.

If a higher-CR undead is within the 30-foot range of Turn Undead, which of these statements is correct?

1. The higher-CR undead is turned if it fails the save, and is unaffected if it passes the save.

2. The higher-CR undead creature is unaffected either way.

Answer 1

The only affected undead are those who fail their save.

Roll a d20 save for each undead

{in your question} The zombies in the area that fail the save are instantly destroyed. The zombies that passed are now turned and will move as far away as possible during their turn.

Not quite.

Channel Divinity: Turn Undead

Each undead that can see or hear you within 30 feet of you must make a Wisdom saving throw. If the creature fails its saving throw, it is turned for 1 minute or until it takes any damage.¹

If the creature passes its saving throw, it is unaffected.

Destroy Undead.
Starting at 5th level, when an undead fails its saving throw against your Turn Undead feature, the creature is instantly destroyed if its challenge rating is at or below a certain threshold, as shown in the Destroy Undead table.²

\begin{align} \text{Cleric Level} && \text{Destroys Undead of CR}\\ \hline 5^\text{th} && 1/2 \text{ or lower}\\ 8^\text{th} && 1 \text{ or lower}\\ 11^\text{th} && 2 \text{ or lower}\\ 14^\text{th} && 3 \text{ or lower}\\ 17^\text{th} && 4 \text{ or lower}\\ \end{align}

If the creature passes its saving throw, it is unaffected. Undead only are forced to move away, or be destroyed, if they fail their saving throw.

Example:

Four zombies and a wight (CR 3) are approaching the level 5 cleric. The cleric Turns Undead.

All five roll their saving throw (let's call the DC 13 for illustration purposes)

Zombies roll 5, 9, 17, 13, so two are destroyed and two are not affected at all. They keep on coming, moaning "Brains!"

The Wight rolls an 11. It runs away, since its CR is too high to be destroyed and it failed its save. Had the Cleric been level 14, then the Wight (who failed its save) would have been destroyed.

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¹ Basic Rules, p. 24
² Basic Rules, p. 25

Answer 2

Neither

The Destroy Undead feature replaces what happens when a creature fails the saving throw. It does not say anything about applying an effect to creatures that pass the save.

So the potential outcomes are:

CR 1/2 or lower and failed the save:

These creatures are destroyed.

CR 1 or higher and failed the save:

These creatures are turned and will run away from you

Any creatures that pass the save:

Nothing happens to these creatures; they passed their save and Turn Undead does not affect them in any way.