Hi Fabio,
Thank you for contacting Syncfusion support.
We have checked your query. We are unable to reproduce the reported “SelectedItem to null when I change TabItem” in our end. For your reference, we have attached the sample in below location. In the attached sample, the focus is present in the selected item when we move into two different tabs. Could you please refer it.
If you are still facing the issue, could you please revert by modifying the attached sample based on your application along with the replication procedure? This would be helpful for us to provide an appropriate solution.
Please let us know if you have any query.
Regards,
Muthukumar K