I put about $400 into a 401k account, but the balance still says $0. Likewise, the vested balance is also $0. Why is this?
If this is a very recent deposit give it a few days.
For me I was paid on Friday the 14th because the 15th is a weekend day. So the pay stub noted that there was a 401K contribution from me, and the expected match amount from the company. Yet on Saturday morning it wasn't reflected in the 401K account. With Monday being a federal holiday I don't expect to see it until Tuesday.
Otherwise contact HR.