As a TS holder, i have been interviewed many times…both for myself and as references for other. There is no way a person can remember every single detail. I have had 2nd to 5th repeat interviews where they have found something that was omitted. I was honest and said I forgot and then gave them all the details i could remember.
I think part of the investigation being face to face is to judge how honest and forthcoming you are. Did you “intentionally” forget or was it an honest oversight. Character always matters.