What deps and applications are you using? I faced what seems like it could be a similar issue that I solved by moving away from listing the applications and instead using extra_applications: Fix application list by axelson · Pull Request #196 · BlakeWilliams/Elixir-Slack · GitHub
Actually looking at jose, it looks like it has the same issue
https://github.com/potatosalad/erlang-jose/blob/80551fc36abab81b6fac798e112a9c1a644b60f1/mix.exs#L25
And it could be fixed by either adding :poison to the list of application or moving the the :extra_applications approach.
