Originally Posted by radonc1

This also happened to me several years ago. I spent a silly amount of time with agents trying to figure out why my TSA precheck wasn't working. I finally got someone to explain what was happening.

When you get SSSS on an international segment, all expedited checks are cancelled for those on-ward segments attached to the international itinerary.

Thus, your segments associated with the SSSS travel would all have their TSA precheck eliminated and you have to go through regular check-in.

However, your next day travel on another ticket PNR will return you to your original TSA status.

Hope this helps.