This is actually mentioned (buried) in our docs.
If a user uninstalls then later re-installs Guardian, they may be prompted to enter their recovery code. If the recovery code has been lost, the user can perform a new installation of the app by disabling automatic restoration of their Guardian backup. To do so, the user will need to uninstall Guardian, temporarily disable automatic restoration of backups within their device settings (steps to do so will vary according to the device), then re-install the app. They will then need to add their MFA account(s) to the app as if performing a first-time setup. If automatic backups or automatic restoration are not enabled on the user’s device, re-installation of the app will not prompt for a recovery code and the user will be required to add their MFA account(s) as in a first-time setup.
It looks like there may be a lingering cloud backup causing this.