First, make sure you are using the latest version of our app. You can do this by going to the App Store or Google Play and seeing if there is an update available.
If keeper functionality is still not working for you with the latest version of the app, try saving your keepers on the web version of Draft Wizard, then loading your league in the app. The keepers should carry over.
Note that resyncing your league or your keepers may erase your keepers if Draft Wizard was unable to get your initial keeper data from your league host. If you are able to save your keepers, it's recommended that you do not resync your keepers or your league.