There are a few things that contribute to the State and Local Taxes limitation of $10k: like you mentioned the state income taxes from your W-2, and your property taxes are included. Also included are any local taxes from your W-2, some state disability payments (like California SDI), any estimates you paid to your state or city, any payments you made in 2018 to your state for a 2017 balance due, and your personal property taxes like your DMV fees. 

For your question about only $8k showing, it depends where you might be looking in TurboTax as to what is being included. I would recommend reviewing the actual tax return before filing, and looking at Schedule A, line 5e to confirm that your deduction is being calculated as the full $10k.