Hi @ Dan
Welcome to our forum!
Based on my research, unfortunately, it is not currently possible to sync the System taskbar calendar with the new Outlook calendar. Please kindly understand that many functions are not designed at present. To get this feature more quickly, I have found a post in feedback collection website and you could vote for it. Many features of our current products are designed and upgraded based on customers’ feedback. You can also make suggestions on that website and hope Microsoft will notice this in the future. Thank you for your understanding and support!
In addition, there is an official statement referred that ‘We will replace the Mail and Calendar apps in Windows with the new Outlook for Windows by the end of 2024’, and it may be related to your question, you may feel free to refer to this article.
Hope it helps!
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