Currently when using Sophos Anti-Virus, Sea of Thieves will be prevented from running due to a malicious code warning. While this is being investigated by the Sophos team, please see the following article and scroll down to the Sea of Thieves section for how to allow list Sea of Thieves within Sophos:
Sophos Antivirus - Allowing games to run along with Sophos Home
After accessing Sea of Thieves with Sophos enabled, if you do receive a crash, please also disable the anti-virus entirely while playing to prevent further crashes.
