Is it normal for California to change your Tax Return after submitting? I had to fax them my W2's and 1099's and they Revised the Balance. Refund of $307 to owe them $480

After months of not receiving my refund I reached out the the CA Tax Board and they said they couldn't verify my withholdings. I Faxed them my W2's and 1099's and this week I got a notice of Tax Return Change - Revised Balance. Instead of getting a refund of $307, I owe them $480.28. How did Turbotax get it so worng?