That’s a rather succinct challenge. Any evidence? Has there been any {Qoylu’} references in canon of a PM time?
The quoted snippet from the HolQeD article says "Originally, this was a statement of time in the traditional Klingon system, but it is now also used for the 24-hour system." That seems to support the claim that {Qoylu'pu'} is *probably* used with the 24-hour clock rather than the 12-hour one, because we're not told anywhere that it's used with the 12-hour system (unless the "traditional Klingon system" happens to be a 12-hour one, which seems unlikely). The quoted sentence comes right after the {cha'logh Qoylu'pu'} example, which it says means "two o'clock" (which the quoted sentence thus establishes as 2 a.m. rather than 2 p.m.).
The article begins by stating in the second paragraph that "There are 24 hours in a day", with no mention of a 12-hour system. The only other example is {chorghlogh Qoylu'pu'} "eight o'clock". Since the only examples we have are for hours less than 12, we don't have any examples of a a p.m. time.
But let's turn this around. The article says the system is used with a 24-hour clock. Is there any evidence that it's used with a 12-hour one? If so, how does one distinguish "2 a.m." from "2 p.m."?