Can you share the output of elixir --version? Even if you have OTP 27 installed, your Elixir version could’ve been compiled with an earlier OTP.
EDIT: Actually, that doesn’t seem to matter. Even with Elixir 1.17.0-otp-25, I’m still seeing the following:
$ mix new ppicom && cd ppicom
$ elixir --version
Erlang/OTP 27 [erts-15.1] [source] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:1] [jit]
Elixir 1.17.0 (compiled with Erlang/OTP 25)
$ iex -S mix
Erlang/OTP 27 [erts-15.1] [source] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:1] [jit]
Interactive Elixir (1.17.0) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)> Mix.ensure_application!(:observer)
:ok
iex(2)> :observer.start()
:ok
