As Yandex is not providing official Yandex API for "music", we have to deal with a workaround, which don't work for all users.
Unfortunately we don't know why some Yandex Music accounts can't be logged to Soundiiz right now; still trying to figured out.
If you encounter an "Invalid Credentials" error while trying to connect Yandex Music to Soundiiz, first make sure that you are using the Yandex account password. When Google or VK is linked, you need to create a password in the Yandex account settings and use it when trying to link Yandex Music to Soundiiz.
If you have two-factor authentication enabled, use only the one-time password from the Yandex app in the "Password" field.
If the above two points do not apply to you, repeat the following steps:
- Enable two-factor authentication.
- Go through all the steps to change two-factor authentication.
- Relogin to your account.
- Turn off two-factor authentication.
- Give another try on Soundiiz.
If still not working after that, it means that we are not able to login to your account.
Thank you for your understanding.