The <fr:assertion name="funder_identifier"> tag was previously nested inside the <fr:assertion name="funder_name"> tag. Instead, put it directly inside the <fr:program name="fundref"> tag. It seems to be valid also, assuming the nesting was not correct, but still accepted by Crossref.
The
<fr:assertion name="funder_identifier">tag was previously nested inside the<fr:assertion name="funder_name">tag. Instead, put it directly inside the<fr:program name="fundref">tag. It seems to be valid also, assuming the nesting was not correct, but still accepted by Crossref.