A trading pause typically lasts less than an hour (but can be longer) and is called during the trading day to allow a company to "announce important news or where there is a significant order imbalance between buyers and sellers in a security."
A trading halt can last up to the end of the following trading day, but not longer, so usually if it's going to take longer than 30 to 60 mins, a company must request a trading halt (instead of a trading pause, trading pauses usually being enforced by the ASX themselves when they require some quick clarification or the company has notified the ASX that they are about to announce something material), and if that halt needs to go beyond the end of the following trading day, the ASX will roll them into a trading suspension, which can last as long as they like.
In this case it seems that the ASX were not happy with the three revisions to JEPI's distribution schedule and the fact that the last one that was lodged just before the trading pause was still "Estimated" (in the heading at the top of the far right column of the first table) despite the ex-date previously being that very day, but being moved to the following day in JEPI's notice. The ASX were likely also concerned with that very late change of the ex-div and the record dates.
I don't think the ASX were happy with the following two notices after the trading pause either, as both were "estimated" also. The final one, at 2:43pm on that day (2nd Jan) had the word "estimated" removed and the numbers had indeed changed, and so had the ex-date and the record-date, which seems to have satisfied the ASX's concerns, but seems like fairly sloppy work by JEPI.
In my experience, it's the ASX that places companies in trading pauses, and usually only for a short time on a single trading day. If a company wants their trading paused, they have to request a trading halt.
And it would be great if S&P recorded ALL trades eh?!? For both the ASX and Chi-X. The whole idea of allowing Chi-X to operate here was to open up competition and try to keep fees lower by presenting the ASX with a competitor, however it causes confusion at times, particularly when a share price moves up or down based on Chi-X trading and S&P refuse to acknowledge that, as happened with one of the companies (AHC) in our Strawman high conviction portfolio at the end of November when I was setting up the portfolio in Sharesight. (Sharesight also appear to use S&P Global for their data which often does not include Chi-X trades).