I would suggest changing your create_entry function to look like this:

sub create_entry {
    # If only two fields are present, the index must
    # be "expired" (rather than expiring.)
    $_[1] = 'expired' if @_ == 2;

    my ($tape_id, @rest) = @_;
    push (@{$tape_index{$tape_id}}, [$tape_id, @rest]);
}
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The problem you're experiencing is that when you have a line like:

 ST4910 (FROZEN)
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you are only getting two fields in your hash. The tape_id, and "(FROZEN)" for the expired field. You then are searching on the "expired" key, which is not present. By changing your create_entry function to the above, both the "expired" and "expires" keys will be properly created.