Q: "In Peer Review" without assigning the AE. What does this mean?
I submitted a paper to IEEE Transactions. For three weeks, the status had been "AE: Not Assigned; ADM: *****; Submitted". Now, the status has changed to "AE: Not Assigned; ADM: *****; In Peer Review". Is it possible that the manuscript is in peer review without assigning the AE?
Submission statuses on the manuscript submission portals may vary from journal-to-journal. In general, the AE (Associate Editor) is assigned to check the suitability and novelty of the manuscript, and whether it should be sent out for peer review. Once the peer review process begins, the AE is responsible for overseeing communication between the author and the reviewer(s), to ensure a smooth progression and ultimately deciding the fate of the manuscript based on the reviewers' comments.
In this particular case, the status "AE: Not Assigned; Submitted" simply implies that the AE is not finalized and there has been no advancement since the manuscript was submitted. Coming to present day status, the AE is still not assigned but the manuscript is undergoing peer review. It can be an indication that the Editor-in-Chief is handling the communication himself and that your manuscript has been sent for peer review.
That said, there is nothing to worry about at this stage. The peer review process does take time. Wish you good luck for your publication journey.