Hi @Marcus Dudáš ,
Thanks for your reply!
Looks like your Mail & Calendar Apps have been Replaced with New Outlook for Windows, you can refer to this article to learn more about New Outlook: Mail & Calendar Apps Will Be Replaced with New Outlook for Windows December 2024.
It seems the problem is that the New Outlook doesnt even have implemented synchronisation with the windows account itself, meaning that if i create some new item on the taskbar callendar - it writes it on the windows account that is not accessible in the new outlook.
According to your description, you can try to add the windows account to New Outlook to check if the calendar will sync.
On the other hand, if you prefer to use the previous Mail and Calendar apps, you can go back to the current Mail and Calendar apps by clicking the toggle in the new Outlook for Windows.
Hope to help you!
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.