Hi Mushtaque,
Thank you for your interest in Syncfusion products.
I was able to reproduce the issue with the wrong positioning of Form when the state is maximized.For now,you can change the StartPosition property of RibbonForm to FormStartPosition.Manual and make sure that the Location property is having coordinates 0,0 [Default Value]so that the form occupies the whole working Area.
this.StartPosition = System.Windows.Forms.FormStartPosition.Manual;
I have logged a bug report in this regard and you can track the progress of bug fix through this
link.Meanwhile,we will analyze the issue in depth and let you know an approximate time needed for addressing this issue.
Kindly let me know if this does not satisfy your requirement.
Best Regards,
Anu.