Just wanted to update that it is now showing up again, next one is 5:00pm (EDT?). The maintenance must have fixed it or they added a hotfix to it without patch notes. It wasn't there prior to this patch we just had, that is for sure.
I was going by the in game calendar, that blogspot calendar is way too cramped and "busy" for me to use. The in game calendar said 10am in game, which if the in game calendar time is localized, then that would have been 10am EDT.
I scrolled as far into the future of the calendar that I could, no where-in was the Path to 2409 event listed. Prior to today's patch, the 19th, that event would appear multiple times a day.
This is the same pattern we've had for a week, since the Season 6 patch dropped.
The Subspace Agenda site calendar has many options to make your view more customizable to what you want to see, whether it's the default weekly calendar, a daily "agenda" calendar, or a monthly calendar.
Part of the reason why I have so many calendars on there is so you can pull up the dropdown menu and filter out what you don't want to see. In your case, the "Path to 2409" event is on the STO Miscellaneous Events calendar (because it doesn't revolve around dilithium, group, or fleet play), so you can pull up the dropdown menu and filter out everything but the miscellaneous events and it should be much easier to see the specific items you're looking for.
Looking at the overall calendar again, it appears that the sequence of events within each day (barring the STF's and Defera Invasion) is exactly the same, but shifted 9 hours forward or 7 hours back each day, creating a 15 or 31-hour cycle (even though some specific events within that cycle occur twice as often). Because we're also dealing with 24-hour days and 7-day weeks, that also means that each entire week will be shifted an hour from the previous week, and you won't see another week with the exact same schedule for 24 weeks!
TLDR; If (for example) you're looking to play "The Path to 2409" from only 11am-12pm PST on Sundays (and I know someone here will claim to be that person), you're not going see it on that exact timeslot again for 24 weeks from this past Sunday (unless the schedule changes again)
Alternatively, if say, day of the week doesn't matter to you but time of day does, the next day "The Path to 2409" would appear in the 11-12 PST timeslot would be 8 days from the last time it showed up in the 11-12 PST timeslot, or... next Monday.
**P.S. I do think you may have a point in that it at least looks like there is an error in the scheduling for the 2300 (PST) timeslot for 7/19 where it should have been a "Path to 2409" instead of another "Time to Craft!" event