@MarkBaker, @Progi1984, I'd like to contribute more, at least to fix all unit tests, but I am a bit concerned by the lack of feedback I got so far. It seems you are all pretty busy, or maybe on holidays. And I know that maintaining PHPExcel while refactoring PHPSpreadsheet is no small task. But have you considered adding someone to the team ? Perhaps someone that could "only" help triage issues so you can focus more on code ? or someone who would be willing to help coding ?