Have you added someone to a Matter-connected Slack channel, but you don't see them in your Matter workspace (the web app) yet? No need to worry. If they are in the Slack channel, you've done your part.
Who can use this: Workspace Owners and Admins on every plan. Slack only.
For an overview of the whole feature, read the Matter setup and rollout guide for Slack.
The reason you don't see them in the web app right away is that we can only sync the web app with the Slack channel every 24 hours (once a week on the Free plan). This is due to Slack API limitations.
You can wait until the following day, or if it's urgent, you can email support@matterapp.com, and we can manually run the Slack sync for your web app.