Hi Hilty,
We are unable to reproduce the issue from our end. Please refer to the sample from the attachment for your reference.
It seems that you may have using custom style in your sample. If you are using any custom style, please share the code snippets of the style.
If we have misunderstood your query, please share the demo or more information about your issue so, that we can prompt a better solution.
Regards,
Gokul T.
Attachment:
WpfApp1_d5e19a09.zip