Oxygen 4.0.4 is a minor bug fix & tweak release. Only one change was made between the beta and the RC: a fix for an issue that caused ID assigned styles on Code Blocks rendered via templates not to be output on the front-end.
Existing users can download Oxygen 4.0.4 RC 1 in the customer portal.
Before using a release candidate in a production environment, backup your site. While release candidates have been tested extensively and are considered stable enough for production environments, you should always proceed with caution when using any alpha, beta, or RC version of Oxygen or the associated add-ons. We will provide official support for sites running release candidate versions of Oxygen and the associated add-ons. If you encounter bugs, please report them on GitHub.