I saw a report for a similar issue of skipping school/work on a reload, but this is different and happens even if I haven't reloaded a lot, so I'm making a new report.
Randomly during gameplay I will get a popup asking if I'm sure a teen should skip high school, usually shortly after I've told them to go to high school. I select "No" on the popup because I don't want my teen to skip school. My teen immediately comes home with no way to go back to school that day.
I play on PC with mods removed. I have High School Years installed and I usually turn off high school follow messages for teens, so it could be HSY related, but I'm not 100% sure.
One time this pop-up appeared when a fire started on the home lot right after the teen was off to school, and another time it appeared right after I had loaded into a household in the middle of an school day and the teen was still at home so I told him to go to school. It has happened more times but I don't remember the circumstances. Every time this has happened, I have had the high school follow messages turned off.
Steps to replicate the issue: Ask a teen to "Go To School" from the career panel. A pop-up appears saying "Are you sure you want [teen] to skip school?". Select "No". Teen comes home anyway.
This pop-up has always showed up out of nowhere without me clicking anything that would make the teen skip school. I don't know if they would still skip school if you make the pop-up appear on purpose and then click "No".