Hi Adam, I'm sorry you are having an issue. Since optical cables are fiber and can get damaged, I would try to replace the cable to see if you are still having an issue. If it continues with a new cable, then I would suggest contacting Samsung Support. Please reach out to Samsung Support via any of these options:
Phone: 1-800-SAMSUNG
Available 8 AM - 12 AM EST 7 days a week
LiveChat or Text: https://www.samsung.com/us/support/contact/
Facebook Messenger: https://www.facebook.com/samsungsupport
Twitter: https://twitter.com/SamsungSupport
The Samsung TV Community is also a great resource for getting help from Samsung moderators and customers: https://us.community.samsung.com/ ^Jeremy