If you submit a revised paper to a journal, usually a few things happen before it is sent to the reviewers:
- The paper is checked for trivial problems such as broken links or missing figures.
- The editor at least superficially checks whether you addressed the reviewers’ comments appropriately. For example if you did not address a comment the editor considers to be major, the paper may be returned to you immediately without review.
- The editor decides whether all reviewers from the previous round are required to review the manuscript again. For example, if the editor thinks that you addressed all remarks of one reviewer appropriately, sending the manuscript to this reviewer again may be considered a waste of everybody’s time.
- In some situations, the editor may refrain from reüsing a reviewer from the previous round for other reasons, e.g., because this reviewer is known to be unavailable.
- In some situations, the editor may select additional reviewers, e.g., if in light of the first two reviews, the editor wanted a third opinion anyway, but wanted to give you the opportunity to reviese your manuscript before this.
Depending on the editiorial management system, some or all of these points may be comprised in Awaiting Reviewers Selection. Or with other words: It may as well mean Awaiting Editor’s Assessment.
Another possibility is that the manuscript was already sent to the existing reviewers but one of them declined to review very quickly and now the editor has to select a new reviewer.