In 1990, I got prepared for my very first DOL investigation (audit). I had already been through several IRS audits for clients and had everything organized the exact way with the 2848 on top.
When the DOL rep sat down, I handed him the 2848 and he asked what it was. I told him it was a POA and that was always the first thing I gave the IRS reps.
He said, "We don't care about a POA. We're the Department of Labor and are conducting an investigation. We'll talk to whomever we want and if we don't get answers, we'll get a subpoena."
I never worried about a POA for them again.