This happened to me (and is in part why I'm a tad salty in the comments), I was a H1B and in the process of adjustment of status. While your green card applicat

This happened to me (and is in part why I'm a tad salty in the comments), I was a H1B and in the process of adjustment of status. While your green card application is pending, you're legally in a grey area if your H1B expires. I had to leave for family circumstances but advanced parole took months to process, I figured it would be okay since it was a serious emergency. Upon returning I was told I couldn't re-enter the US because even though my stay in the US was completely legal, I had technically overstayed the terms of my H1B. The USCIS policy and CBP policy differs around this. There's a specific USCIS policy memo that mentions this actually. So I'm now banned, no leniency, no understanding for the situation.