If your eBay account has become disconnect from Sellbrite, it is likely due to a disruption that occurred outside of Sellbrite. Typically this happens when your eBay password is changed, or when you attempt to renew your eBay token while logged into a different eBay seller account in your browser.
Log out of your eBay seller account in your browser
Open an Incognito browser tab.
Navigate to Settings > Sales Channel Integrations
Click "Connect a New Channel"
Click "Connect" under eBay
Follow the connection instructions
NOTE: Do not delete your disconnected eBay channel. From the "Connect a New Channel" page, eBay will already appear connected. Click the "Connect" button anyway.
When finished, you'll be redirected back to your Sales Channel Integrations page and you'll find your eBay channel reconnected.