Why Didn't my event-based rule successfully trigger?

Hi All,

I have an onboarding series that sends zero messages for users who move through basic onboarding on their own, but sends emails and posts to users who get off track.

We have about 10 people a day enter this flow, and for most of them it's working, but I had a case where it didn't work and I'm trying to figure out why that one case did not work before our busy season starts in august.

The piece of the series I had an issue with is imaged here.

Ignore the blue tags and you can see it's a rule at the top left, which is event based. The event is "Assigns homework" in our application. if the user assigns homework within X time, they pass this rule and move on to the right (off screen), but if not passed after X time, the series funnels them down to the post below.

The post below doesn't have to be seen; either way, they are now in contention for the second row rule, which is identical to the first: Assigns homework. IF they now assign homework within X time, they pass the rule on that second row, are tagged as "re-engaged" for my own purposes, and then move on to the right (off screen).

If they don't assign homework within X time, they move down to an email.

etc.

etc.

So, this will send one post and two emails to a user who disengages from the product (over about 17 days of time in total), before tagging them as totally disengaged.

And it will send zero things to a user who takes the expected route of behavior through the app.

And it sends somewhere in between to the average user who maybe deviates or forgets what they downloaded the app for.

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If you've followed this, here's my issue:

with one user, and only one user, the initial top left rule of "assigns homework" never triggered, even though the user did in fact assign homework.

Our app updated the user via rest API and the "homework assigned" event successfully shows up in their profile, and could not have been taken in a period of time before this series, since they have been in this series since they first signed up for our app.

The problem here is that we thus sent them out-of-context posts/emails about "assign your first homework set!" , when they had already done so.

I noticed after the first one and I succesfully removed the person from the series entirely to make sure no more went out, but I have not been able to figure out why this happened.

My best guess is that somehow the event "homework assigned" fired before this person arrived at this block. The previous part of this series has an identical downward-stepping set of items for a different behavior; that behavior is not event based but rather URL based.

My assumption is that the user moved from that URL onto "assign homework" very quickly, and that the series did not register the URL based rule until after they had already "assigned homework." At that point, the series recognized they passed the prior URL based rule, and moved them to this block, and waited for the "Assign homework" to trigger, but it had already triggered.

So, I guess the question is: what is the timing of how a series knows `URL based rule = true` vs how it reads `event = occurred?` and could I have some kind of a race issue here?

thanks for any help, I love series. It's an incredible product within an incredible product and you guys are amazing.