Loop block end line is not greater than first line

What causes this issue?

When defining a loop block, you cannot position the cursor on a line
above the first loop line.

How to fix this error?

To define a loop block, place the cursor on the first line of the block
and press F16. For a multi-line loop, define the last line by placing
the cursor in the last line and pressing F16.

Error message extract from SAP system. Copyright SAP SE.