If your TSA PreCheck isn’t showing up on your boarding pass, there are several steps you can take to resolve the issue and avoid longer security lines.
First, ensure that your Known Traveler Number (KTN) is correctly added to your frequent flyer profile. "After receiving your KTN or when flying a new airline, immediately add it to your frequent flyer profile so it automatically populates into the correct field when booking flights," advises the article.
Next, check for any discrepancies between the name on your ID and your boarding pass. "Any typographical discrepancies... may cause security to note the discrepancy and flag your boarding pass for closer scrutiny," the article warns.