The behavior of the SfRichTextBoxAdv control is initially control loaded without focus (without cursor). It gets the focus only on perform click operation on it. Now, we couldn’t face any issue in this behavior. So, please let us know how you are loading the content to this control and share the sample application with replication steps to reproduce the issue. It will help to provide you the appropriate solution at the earliest.
Note: please let us know the syncfusion product version which is you are using.