Buffer contents cannot be inserted in the column

What causes this issue?

The clipboard contains blocks which lie completely in a row. A column
was explicitly selected as insertion position. Therefore, the clipboard
cannot be properly inserted.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Select the insertion point either explicitly by means of a data cell or
implicitly by positioning the cursor on the required insertion position
outside the area of the lead columns.

Error message extract from SAP system. Copyright SAP SE.