Include
Include the specified configuration file(s). Multiple pathnames may be specified and each pathname may contain glob(3) wildcards and, for user configurations, shell-like
``~'' references to user home directories. Files without absolute paths are assumed to be in ~/.ssh if included in a user configuration file or /etc/ssh if included from
the system configuration file. Include directive may appear inside a Match or Host block to perform conditional inclusion.

I had my Include statement trailing a Host directive so it was being included into that Host's config.