This known issue is closed due to the decommissioning of Blackboard on the 31st of August, 2021

On Mac OSX 10.7 or newer under default system settings, the horizontal scroll bar in the Grade Centre may not be displayed regardless of the browser used.

To fix this issue:

1. Click the Apple icon in the top-left corner
2. Select “System Preferences”
3. Click “General”
4. Under the “Show scroll bars” heading, choose “Always”