Styled vocals need a performer legend.
This multi-performer section differentiates inline vocals but its header does not identify the style slots. Add a performer legend, or remove the formatting if the section no longer needs performer differentiation.
Example
[Verse]
<i>Second voice</i>[Verse: A & <i>B</i>]
<i>Second voice</i>The fix
In the workbench this finding carries one control, labelled Remove performer formatting. The fix is classified as safe, so pressing it applies the edit directly — one press, one undo step.
Source
The guideline this rule enforces, as cited on every finding it reports:
Use song part headers verified Section headers, performer legends, and four differentiation styles