As I mentioned in my original question, I double posted this question on the Biblical Hebrew forum. I received this response from Michael W Abernathy, affirming the NIV rendering:
מַדּ֗וּעַ מִ֭שַּׁדַּי לֹא־נִצְפְּנ֣וּ עִתִּ֑ים וְ֝יֹדְ֯עָ֗ו לֹא־חָ֥זוּ
יָמָֽיו׃ Halot gives multiple meanings for צפן including keeping,
storing, reserving, treasuring, etc. A literal translation could be,
“Why aren’t times reserved by the Almighty?” As for the aspect of
judgment, Keil and Delitzsch comment that עִתִּ֑ים appears to be
comparable to the Arab ‛idât, “which signifies predetermined reward or
punishment.” Again Halot suggests it means judgment in several
passages, “time of judgement, time of the end לָבוֹא עִתָּהּ Is 1322
(of Babel), Ezk 223 (of Jerusalem), עֵת אַרְצוֹ Jr 277; עֶת־קֵץ Da
817, = עֵת קֵץ 1135.40 124.9; בָּא הָעֵת Ezk 77.12, עֵת עֲוֹן קֵץ the
time of final punishment 2130.34 355.” So, “Why aren’t times of
judgment reserved by the Almighty?” seems quite reasonable.
Ludwig Koehler et al., The Hebrew and Aramaic Lexicon of the Old
Testament (Leiden: E.J. Brill, 1994–2000), 901.
That raises my confidence that the NIV ("Nearly Infallible Version") is on the right track.
Brenton renders the Greek like this:
Brenton Septuagint Translation
Job 24:1 But why have the seasons been hidden from the Lord,
[Job 24:1 LXX] (1) διὰ τί δὲ κύριον ἔλαθον ὧραι
Curiously, the Greek changes it from the LORD not disclosing the days set for judgment to the days of judgment being hidden from the Lord!
The NT appears to ignore the Greek here and alludes to the Hebrew reading:
[Matthew 24:36 NASB20] (36) "But about that day and hour no one knows, not even the angels of heaven, nor the Son, but the Father alone.
[Mark 13:32 NASB20] (32) "But about that day or hour no one knows, not even the angels in heaven, nor the Son, but the Father [alone.]
[Acts 1:7 NASB20] (7) But He said to them, "It is not for you to know periods of time or appointed times which the Father has set by His own authority;
[John 5:30 NKJV] (30) "I can of Myself do nothing. As I hear, I judge; and My judgment is righteous, because I do not seek My own will but the will of the Father who sent Me.
[John 8:28 NKJV] (28) Then Jesus said to them, "When you lift up the Son of Man, then you will know that I am [He], and [that] I do nothing of Myself; but as My Father taught Me, I speak these things.
God had not revealed the time of his return. If he knew, he would have told his friends:
[John 15:15 NIV] (15) I no longer call you servants, because a servant does not know his master's business. Instead, I have called you friends, for everything that I learned from my Father I have made known to you.
However, he knew that it would be in the then current, non-overlapping generation:
[Matthew 23:36 NKJV] (36) "Assuredly, I say to you, all these things will come upon this generation.
[Matthew 24:34 NKJV] (34) "Assuredly, I say to you, this generation will by no means pass away till all these things take place.
[Mark 13:30 NKJV] (30) "Assuredly, I say to you, this generation will by no means pass away till all these things take place.
[Luke 11:30, 32, 50-51 NKJV] (30) "For as Jonah became a sign to the Ninevites, so also the Son of Man will be to this generation. ... (32) "The men of Nineveh will rise up in the judgment with this generation and condemn it, for they repented at the preaching of Jonah; and indeed a greater than Jonah [is] here. ... (50) "that the blood of all the prophets which was shed from the foundation of the world may be required of this generation, (51) "from the blood of Abel to the blood of Zechariah who perished between the altar and the temple. Yes, I say to you, it shall be required of this generation.
[Luke 21:32 NKJV] (32) "Assuredly, I say to you, this generation will by no means pass away till all things take place.
Later, he was given a revelation from God of many of the specifics of his return:
[Revelation 1:1-3 NKJV] (1) The Revelation of Jesus Christ, which God gave Him to show His servants--things which must shortly take place. And He sent and signified [it] by His angel to His servant John, (2) who bore witness to the word of God, and to the testimony of Jesus Christ, to all things that he saw. (3) Blessed [is] he who reads and those who hear the words of this prophecy, and keep those things which are written in it; for the time [is] near.