Hey Colby 👋
That's not possible today. Custom dimensions are scoped to individual charts, so they don't show up in the dashboard filter picker.
We do have an open feature request for this:
https://github.com/lightdash/lightdash/issues/10259
I'll upvote so you'll get updated in this thread when we work on it!
In the meantime, if you need this dimension as a dashboard filter, the best path is to define it in your dbt project directly (or use dbt write-back to promote the custom dimension into your project:
https://docs.lightdash.com/guides/developer/dbt-write-back). Once it's an explore-level dimension it'll be available as a dashboard filter across all your tiles.
Let me know if you have questions on setting that up!