Hi wishonastar,
Welcome to Community! Having the option to categorize your receipts is a great feature in the mobile app, that saves valuable time when reviewing your transactions in QuickBooks Online. When categories are missing only in the mobile app under snap receipts, there's a couple of things to look into. I would be happy to help!
Initially, I recommend refreshing the app. If you get the same result, uninstall the app, reboot your mobile device and then install the app to ensure you have the most recent version.
If the issue persists, please contact us outside of this forum, so we can work with you in real time and get this resolved as soon as possible!
Touch base with us again, if any other questions come to mind. We would be glad to assist!