Welcome to the monastery Sophienz

At first glance it not seems a behaviour related to flush or autoflush the filehandle and about this (never used) method i read Turns on autoflush, print ARGS and then restores the autoflush status of the IO::Handle object. that seems also not so efficient while itarating over array.

Anyway as the famous motto says 'Bad data ruins your day' check your array using something like Data::Dump dump or dd method: is better of the core Data::Dumper.

HtH
L*