Several years ago Homepass launched an updated app and since then we have been slowly retiring our classic app from use. Soon the classic app will no longer work for check ins and continuing to use it could risk loss of data.
If you are a long term user of Homepass it's possible you may have both apps installed on your device. You can use the version number to check which app you have. You can find this by going to Settings, then About.
If you are on iOS and the number is 3.7.28 or less or on Android and the version number is 3.8.0 or less then this is the classic app. You should delete the classic app from your phone and install the new app for iPhone or Android.