Hi Bharath,
Greetings from Syncfusion.
We able to reproduce the issue and we confirmed “NullReferenceException occur when setting CrossesAt to primary axis without having secondary axis” as an issue. We will provide fix for the reported issue at our next weekly update on 20th October 2020. We appreciate your patience until then.
If you have any more specification/precise replication procedure or a scenario to be tested, you can add it as a comment in the portal link above.
Regards,
Saravanan.