I was about to ask this too. I have a novel being written with the beta, and I need to create a timeline for it.

I'm a user of Scrivener and Aeon Timeline. I'm using Aeon version 2.3.16 and Scrivener version 2.9.0.17 (Scrivener 3 Beta 17). I'm able to sync with no problem. Kudos to the developers on both teams!

Hi, We can't guarantee that the syncing process will work with Scrivener 3 betas as we don't constantly test it with every new Scrivener beta release. As a user stated above, we do believe that it currently does work, but we can't guarantee there won't be problems. If we are alerted to any issues, then we do attempt to fix them, so let us know if you have any problems. Jess