I think the sentence is talking about mankind in general (in pursuit of new horizons), so there would be no agreement.

Bonjour Alan, Is your question about a specific kwiz question? Please resubmit and provide the quiz question you have concerns about. Bonne chance.

Hello Ron, The question was no.8 in a C1 advanced focus test. We were asked to fill in the blank in the sentence, "En tant qu'Hommes, on est toujours...........à la découverte de nouveaux horizons".

I do recall that specific question and as I recall I had an incorrect response. I agree with your observation that being male, the verb agreement should be correct. Wish I could be of more help on this. J'espère que ma réponse vous aiderait. Bonne chance et bonne continuation dans vos études en français, la langue de Molière et qui a été utilisé par le monde depuis l’époque d’Hugues Capet

I also had trouble with this specific kwizik question, I think because the english translation "As Men, we..." leads me to understand that the group of people in questions is specifically male. Maybe the translation could be "As humans, we..." or something similar? I do understand the sense that it is representing mankind... just the nuance is a bit less clear, I guess. Hope this makes sense.