"I also think ..." only works there if someone else has already said that they think there is one more issue.
John: I think there's one more issue.
Jane: I also think there's one more issue. I wonder if we're thinking about the same issue.
John: I think that's answered all our questions.
Jane: I'm not sure. I don't think they really answered the one about finance. Also, I think there's one more issue - what about the health and safety regulations?
Student or Learner