The timeline feature in Work Management projects is not as full-featured as the roadmap in software projects. For one, tasks do not roll-up to their parent epics. There does not seem to be a method to group tasks together using versions either. Compare:

Roadmap:

I thought I was going to be clever and create a "master" project for a team where they could view nice roadmaps for their projects. Nope, roadmaps only work if the issues are in the current project only.

I'm guessing there is no other work-around.
It feels like JWM projects are a little half-baked. I already have users asking if they can just use the competing product that we migrated them away from.