With the release of iOS 11.2.1, the UI for 2STP has begun to degrade. Sending me and many others on a search for a new app for 2FA.
This tool allows for decrypting the encrypted backups created by 2STP.
If you're looking for a new iOS app, I'd reccommend OTP Auth. It provides a similar experience, shows rapid progress, and has proactive support similar to that provided by 2STP. As a bonus, the backup file format and encryption is well documented over at CooperRS/decrypt-otpauth-files, allowing you the freedom to migrate your codes to a new app if the author gets hired by Apple.
git clone https://github.com/ewdurbin/evacuate_2stp.git cd evacuate_2stp pipenv install pipenv run python decrypt_2STP.py --encrypted-2stp-export <path to your 2STP export>
A demo file
demo.2stp is available for testing, it's password is