function inside andThen() not emitting onComplete()

Here is my stream:

public Completable changeUserPassword(String oldPass, String newPass){
        return firebaseAuthRepositoryType.getCurrentUser()
                .flatMapCompletable(fu -> firebaseAuthRepositoryType.reAuthenticateUser(fu,fu.getEmail(),oldPass)
                   .andThen(firebaseAuthRepositoryType.changeUserPassword(fu, newPass)))
                .observeOn(AndroidSchedulers.mainThread());
}

Problem is the function inside andThen() never calls onComplete()? and the stream is "stuck" there. The return type of changeUserPassword() is Completable.

I tried to change out the function inside andThen() to Completable.complete() for debugging purposes but I saw the same behaviour. It still never "completes" and gets stuck in andThen()

Am I missing something here? Any suggestions?

The flow of the stream is supposed to be:

• getcurrentuser(): returns user ->
• reauthuser(user): returns Completable.onComplete() ->
• user.changepass(): returns Completable.complete()->
• return Completable

from function inside andThen() not emitting onComplete()