A new or updated I-693 ids required if something was missing from the first
It might be related to the COVID vaccine. If it was not required the you did your originally do your I-693, that could be the issue. Or maybe they need proof of the second dose.
Also sometimes the original I-693 has the things missing. Basically at AOS it is looked at again. but it is looked at with current requirements and not the original requirements you needed for the K=1