Anyone else’s due date not advancing?

And no I am definitely NOT checking the box that says "do not advance my due date". Never have.

Currently have 8 federal loans all serviced by Nelnet. My strategy has been to pay extra whenever I can and advance the due dates as far out as possible so I have a few months' breathing room if needed. My next monthly payment is due Nov. 2026. I've still been paying monthly with however much I've got, and just advancing the next due date further and further.

A couple weeks ago, I realized that none of my payments from 2026 had advanced the due date on any of my loans. I called Nelnet, spoke with representative, she told me she'd "try to put in an order to advance my due date, but there was probably nothing to be done since the payment was already processed". She admonished me to make sure not to check the box. I DID NOT check the box. I never have.

I made another payment in late March and another a few days ago. Just logged in and checked my due dates–still Nov. 2026. Is anyone else having this problem? I'm starting to get really pissed. I work a job where my income is extremely variable month to month. I make extra payments when I can to intentionally kick out the due date so I stay in control of how much I pay and when. I've never had an issue with it before.

ETA: the payments I've made were all more than the monthly payment due, so they should definitely have advanced the date.