Blockers are important ways to let your main contacts for the brief know that an issue came up, which is blocking your shoot from happening. It's always a good idea to send additional communication using the in-app messaging function on the right to give more context to your blocker.
To add a blocker:
1. Click on your brief from your brief list
2. Click on your "Production" tab
3. Click “Add a Blocker” on the right side of the page, and select the blocker you would like to add.