Editing text and leader line is changing.
When changing text the leader line is going through the text.
Once a note gets converted to DWG, such control over text gets lost. This is how a leader works in ACAD.
ACAD lacks of the automatic text attachment justification as we do. So if this file was originally an AutoCAD file that is why the line is showing through the Text.
This is a limitation that AutoCAD has. This is a WAD (works as Designed). If you place a new note, then this will correct the problem.