Please follow the steps:
1. Run the attached sample project.
2. Move the form to a monitor with 125% DPI scaling.
3. Resize the form to make the spreadsheet bigger. You will notice that the column/row headers are missing for the last column/row headers.
I have also updated your Telerik points.
Currently, due to the specificity of the issue, the possible solution that I can suggest is to disable the DPI scaling. We will do our best to introduce a fix as soon as possible in one of the future LIBs.
I hope this information helps.