Suggestion 870 Missing named Inline citations seems to enforce a very strict interpretation of mark up, requiring no spaces around the = sign in ref tags.
<ref name="ABCD"> ... </ref>
followed later by
<ref name = "ABCD"/>
generates the suggestion, and removing the spaces around = deals with it, but this seems overly strict as their presence makes no difference to the display of the reference. Whitespace like this is allowed in html tags.