We are in the process of completely updating the underlying technology that forms the basis of the writing experience in First Draft Pro.
As a result of the update, projects created before the 25th of December are currently experiencing an issue when splitting a scene in the manuscript that results in a text malformation that looks like this:
We recommend that you avoid splitting scenes in existing projects until we've resolved the issue. If one of your projects is already affected, please reach out via the in-app chat function and let us know.
We are currently investigating this issue, and apologise for the inconvenience.