This sounds like a terminological issue. Without further context, I would assume that "lead author" means the last/senior author, not the first/junior author. B

This sounds like a terminological issue. Without further context, I would assume that "lead author" means the last/senior author, not the first/junior author. But I guess that's a life sciences tradition. "Who actually did the research" is not always an accurate description of the first author. There are plenty of papers, where the last author had already contributed enough to justify authorship before the first author was even hired. You often need to develop the idea and get preliminary results to convince someone to fund the project, before you get the money to hire the first author to work on the idea.