Hi ayoung,
If this is a custom screen, I suggest you take a look at the actions on the save button of the stock screen that are used to populate the updated values. Here they are.

If you’re having this issue on the stock invoice screen, please give our support number a call at 1.888.925.6238 x2 and we’ll be happy to investigate this with you. I hope this helps.
-Audisho