Hi George,
Thanks for contacting Syncfusion’s support.
Could you please provide the following details?
1. To localize the headertext to which language?
2. What are all the culture you have register in startup.cs?
3. Do you have RC1 or RC2 update?
4. Do you have registered translating text in resource file?
5. Share the simple sample with the specified requirment.
It will be great helpful for us to analyze about the issue and provide you a response as early as possible.
Regards,
Saravanan A.