I'm staggered as to how you can equate prophecy with mysteries.
And I am staggered that you
cannot see that mysteries are associated with prophecy. Allow me to assist you:
First of all, if you hadn't noticed, it forms part of the same "if" statement dealing with prophecy and therefore clearly connected with it.
Secondly a mystery (mustérion) is a secret of God that is hidden and awaiting to be revealed to mankind. Those are clearly things that can, if God so chooses, be revealed in prophecy.
BDAG Lexicon
μυστήριον
...
① the unmanifested or private counsel of God, (God’s) secret, the secret thoughts, plans, and dispensations of God (SJCh 78, 9; τὸ μ. τῆς μοναρχίας τῆς κατὰ τὸν θεόν Theoph. Ant. 2, 28 [p. 166, 17]) which are hidden fr. human reason, as well as fr. all other comprehension below the divine level, and await either fulfillment or revelation to those for whom they are intended
And here is a clear example of Paul revealing a mystery in a prophecy:
Rom 15:51 "Behold, I tell you a mystery; we will not all sleep, but we will all be changed, in a moment, in the twinkling of an eye, at the last trumpet; for the trumpet will sound, and the dead will be raised imperishable, and we will be changed. "
Thirdly if "knowing all mysteries" was a separate example of Paul's then it would have it's own "if" qualifier like the others.
Fourthly if "knowing all mysteries" was a separate example then like the other examples it would be a spiritual gift. I don't see "knowing all mysteries" listed anywhere as a spiritual gift.