So I've been chugging along for years now thinking I'd been doing everything right because no carrier adjustments were showing up in my account history and I'd never been alerted to any adjustments. WRONG. I found out the hard way the other day that you need to log into stamps.com, go to reports, then balances (left side) then transactions and scroll through hundreds or thousands of transactions to see adjustments. There's also no way to filter for them.
I got hit with over $800 worth of carrier adjustments last year. If I'd have known about this sooner, I could have taken proactive action to avoid most of them.
There's absolutely no good reason why this information should not be coming up in the account history in ShipStation. I found out from a friend who uses Shipping Easy (also owned by Stamps.com) that they appear in her reports. This is basic information that every shipper needs to access.