Message flow on top of message symbol

When I create a message flow, I create a message (or use an existing message if I’ve already created it) and change the Presentation Options/Message Flow Display Options to Overlapping Message Flow. This works, but sometimes the message icon is shown on top of the message flow, and other times it’s underneath the message flow:

This is untidy.
Why does this happen?
How do I get all the icons to appear in front of their associated message flows?
Right clicking the message icon and choosing Bring to Front doesn’t work.

Thanks - Rowan

Hello Rowan,

Seems we cannot generate this issue. Would you mind send me the problematic project file to have a look?

Best regards,