Hangfire server restarts despite App Pool being kept alive

During the day my hangfire server restarts randomly during the day but always at 16 minutes past the hour. I know it’s usually associated with the app pool “falling asleep” but we have a keep alive that requests a page from this site more often than the 30 minute app pool sleep period.

What can cause my hangfire server to restart like this? I checked the IIS logs and there is no app_pool restart or specific event at the times the restart happens. I have no trace of anything going wrong in the server’s event viewer either.