If you got a message directing you to this article, it is because you've generated a timeline where the event date may be in the future, but the actual dates of your timeline items are in the past.
First, the why.
Why would my items be in the past?
This usually happens because you created a timeline where the date in the headline of your timeline is very different from the dates of your individual items.
For example, you create a timeline that you plan to reuse over and over again as a template for your future events. So you set the ceremony date way in the future like you're supposed to (like June 6, 2040), but then when you create individual items, you forget and start giving them dates in a different year (like June 6, 2035).
Then you go to duplicate the template you've made to use it for an event this year. The system will make sure to preserve the spacing for all your item dates to be the same as the spacing for the original template you used. That means for the upcoming event you are planning (let's say the event takes place 10/31/2020), the timeline you've generated will have items in the past (10/31/2015) and after a day, it will archive itself because it thinks the event has already happened.
Note that the date at the top of your timeline actually doesn't have a bearing on the timeline itself. It's the date and times of your individual timeline items that determine when a timeline is "finished" and should be archived.
Now, the how.
How to fix this?
First, to avoid this happening again and again, you'll want to edit the original template you're using. Make sure the dates of all the items are correctly spaced around the event date. Then when you duplicate it to use for future events, you shouldn't have any problem.
Second, if you want to fix the timeline you have just generated before it archives itself, scroll to the last day of your timeline, and edit the day/year of that grouping. Click on the date in the grey bar (for example Wednesday, June 6, 2020) and correct it. Then move up the timeline to fix each grouping of items. We suggest you start at the bottom so that you don't accidentally merge items from one date into another. Start at the last date, then work backwards.
Then, change the date in your header to match the dates of your timeline items.
Third, If you find that your timeline has archived itself before you had a chance to fix it, follow the steps in this article to reactivate an archived timeline. Make sure to fix the date spacing, though!
And if you're really stuck, reach out to Customer Success Team at email@example.com and we'll get you fixed up!