The header of the Panel macro is getting longer than its body when the 'Table fitting' in the export settings is set to 'Fixed Width'.
Steps to reproduce:
Create a Confluence page and add a Panel macro with a title.
Nest a scroll Title macro inside Panel macro including a table.
Set 'Table fitting' in the export to 'Fixed Width' and export the page.
The Panel macro will be exported with the same header and body width and the caption is visible.
The Panel macro header becomes longer than its body and the caption is overlapped by the panel border.