Within my Jira instance I have 2 different software projects. However, I'm noticing that the timelines feature is working slightly differently per project.
When I click into Timelines for Project A, I see a view to create a plan and view all plans:

The timeline is created as expected after selecting the different configuration options:

However, when I click Timelines again under Project A, I see the same view to Create or View a project. Is there a reason the Timeline created under Project A isn't saving to the Timelines view for Project A?
Project B
Project B is also a software project. A timeline has been created for this project, and appears when clicking Timelines when already in the project:

Why when clicking into Timelines for this project do we see a timeline, and not the create plans/view plans screen?
My colleague would like to change the timeline for Project B to include different ticket types that aren't attached to an epic. However, isn't getting the create plan/view plans screen when clicking in Timeline when already in the project. So she is unable to configure the plan for Project B's board.