SerenaHeart

Hm, the timeline did confuse me a bit I thought I filled out everything that has happened so far. I will take a peek and see what else I could add to this for now. 
 
 

It is confusing. On site site timelines and profiles are different. I think your Timeline is fine, but your profile is missing country, so there is no flag. https://www.visajourney.com/profile/324324-serenaheart/

It sounds as if USCIS made a minor error which had to be corrected.......maybe they didn't mark a box.....

This has happened to a few people, and you are right there is rarely any clarity as to why. Most likely explanation, NVC noticed some sort of mistake, and send it back for USCIS to "reaffirm" and correct it, which USCIS did now. You will probably get a new NOA2 with new expiration date, so do not worry about that expiring. Hopefully next week, on Match 19 NVC will forward your approved 129F to your embassy. By the way it will be helpful if you finish your profile and timeline since you are entering part of the process that is very country specific now.

When NVC receives the approved I-129f from USCIS, they check to ensure that it’s been stamped. NVC will occasionally receive a petition from USCIS and it does not have the appropriate approval stamp in the upper left-hand corner. They are also checking to make sure that the three criminal questions have been answered. He noted that there are times when the petitioner will forget to complete those questions and those questions are subsequently missed by the adjudicator.  In both of these instances the case will then be sent back to USCIS. If one of these things occur with a case file recently received from USCSI, NVC would know within the first week of receiving the case.