After some investigation... It seems that the presence of the #+bibliography: line is what causes ox-pandoc to fail. Removing this line is sufficient for me to get the export working.
Thanks again, eric -- : Eric S Fraga via Emacs 28.0.50, Org release_9.4.6-607-g185706 : Latest paper written in org: https://arxiv.org/abs/2106.05096
