Logger discarding messages without a trace

Hi All,
I’ve been forced to open a new thread as this issue is quite critical. I will be pushing a patch to production tonight and it’s imperative I resolve this issue.
I’m running Elixir v1.9.2 in production - I observed that log messages are being discarded without a trace or warn in the logger file indicating that they are being discarded. Currently I planned switching the Logger to sync mode so as to avert the messages being discarded.

  1. Is sync mode advised in production explicitly; I know the Logger toggles between async and sync mode
  2. How can I check if messages are being dropped since there’s more entry in the log file indicating messages being discarded.