My Ionic Apps has some issues with cookies and sessions on iOS build. It is unable to store the cookies I guess with iOS 13.1.* versions, but working fine on android, ios on iPhone 6s and 7 versions. Not sure why its breaking on iPad and some iOS devices. Even its not working on simulators.
The app was initially build on Ionic3 but later moved to Ionic4 with cordova. The auth and API systems are using session based from Opencart PHP E-Commerce CMS.