The biography has a <ref> tag after the <references /> tag. See Suggestion 868: Inline citations after tag. The inline citation (i.e., the <ref>citation<ref>) should be in the == Biography == section. As long as there is a <references /> tag the citation content will appear following that tag -- you can see by clicking on Preview when you are editing a biography. Ensure that the placement of the <ref> tag is not part of the Profile Manager's style (see Communicate Before Editing).
From https://www.wikitree.com/wiki/Space:BioCheckHelp