Hi Charles,
Thanks for contacting Syncfusion support.
We have tried to reproduce the reported issue at our end, but the
menu filter pop up is working fine at our end. Please refer to the below
screenshot for more information.

To validate further, please share the below details that will be
helpful for us to provide a better solution.
- Share
your Grid code
- Share
the Syncfusion style theme you are using
- Is
there any style customization for Grid?
- Share
the Syncfusion package version
- Please
share an issue reproducible sample if possible.
Regards,
Pavithra S