There is a known issue users can experience when a staff style without a top staff line, such as 1-Line Staff: Full or Force Hide Staff, is used in combination with a SmartShape. Often the SmartShape will attach itself to the nearest available measure with a top line.
While this issue has been documented, we can recommend the following workarounds in the meantime:
Using Utilities > Move to Next System, move the selected measure to the start of a new system. After the SmartShape has been added, return it back to the original system using Utilities > Move to Previous System.
2. Enter both the note and the SmartShape prior to applying the Staff Style to the measure. For Staff Styles that have already been applied to the measure, you will need to clear the style first with Staff > Clear Staff Styles From... You can reapply the Staff Style once the notes and SmartShapes are re-entered.