One thing you may try is to go to Android Settings - Apps, and in Norton Identity Safe clear the app data and app cache. Restart your device, then check the Accessibility service is on and then sign into your vault. You will have to first sign into your Norton Account, then the vault.
Thanks for the suggestion, tried that but it didn't help.
Next step would be to reinstall the app. Clear the app data and cache as above, then uninstall the app. Restart your device and reinstall the app, and test.