Any reason why the value of my collection would have disappeared entirely [reset to $0.00]?

Each game's value seems to come back piecemeal if I open up that individual game's entry and hit the "save" button, but I don't have the time to do that for hundreds of games one by one. Is there any other way?

Pricing data is refreshed daily and sometimes there's an issue that can result in it disappearing from collections. But it should correct itself