Manuscript status changed from Review in progress to Ready for review
Just a guess, but a reviewer may have backed out so they are back to square 1. Probably no reflection on the paper. It may also been that the editor wasn't satisfied with the review he/she got so started over. Reviewers get busy just like authors. 

Another possibility is that the editor got back inconsistent reviews. 

Be advised that dealing with publishers can be very frustrating. Not the finest aspect of the academic life.