tsa precheck issue

I have had that problem with at least one airline and I now check every reservation individually to make sure my data is associated with that res. You can also have a ticket agent add it at check in but it does not seem to be embedded in the airline reservation site, at least not dependably.

First confirm that your known traveler number (KTN) hasn't expired. Then verify that the KTN is in the airline's system and that all of the details on your airline profile match your official KTN (including your name, passport number, and expiry of GE/precheck). If you recently got a new passport you need to update your GE with the new passport number. If all of that is correct, then a quick stop at the airline desk to ask to have your boarding pass updated with precheck before you head to TSA checkpoint.

Also some airlines don't participate in precheck so if you were on one of those, none of those steps will help you.

And worth mentioning, you are not always guaranteed TSA Precheck. You can randomly be assigned to normal screening, as a precaution.

You may also want to verify your expiration date for TSA Precheck, it may not be the same as GE.

If it’s for an upcoming flight, you can have it added (usually have to call). It’s usually a one-time omission. If I use an airline often, I make sure it using my account profile.

I have had my TSA PreCheck fall off both on Delta and United flights. If I realize before I leave for the airport, I go into my account and re-enter it. If I don't notice until I get to the airport, I go to a check-in desk for the airline and they take care of it.

Getting it restored has never been an issue. I know make sure it is on my boarding pass right after I check-in - usually via the app but on rare occasions at the airport - and it has always been quickly resolved.
To play it safe, I now keep a card in my wallet with all my airline numbers (TSA, frequent flier accounts, etc.) so I have it handy just in case. IIRC, I also have pictures on my TSA number buried in my phone as well.

Had my boarding pass for an Austrian Airlines flight disappear and the check-in agent quickly fixed it and told me this happens periodically with the app. I guess occasional tech issues are bound to pop up.

Forgot to mention - you can go to the TSA web site and check the expiration date to play it safe. All it requires in your last name, DOB and TSA number. In theory, you will get multiple messages before it expires.

All sage advice above. Always double check your ticket once you've checked in. If it's not there, call the airline (if it's the day prior) or have them reissue at the desk at the airport.

What the OP experienced is a feature, not a bug. That is, TSA Precheck NOT happening for you (and for everyone) once in a while is actually intentional.

Security professionals abhor 100% consistency and absolute predictability, at least when it comes to routine screenings. They like to throw a random curveball occasionally. This is one example.

I’ve had TSA Precheck go AWOL out of the blue once or twice (when and where it should have run as expected). Nothing to be worried about, that’s just how they roll.

.
https://www.tsa.gov/precheck/faq

Explains that there is no "guarantee" for expedited screening

thank you all for the info.

On our flight to Istanbul last month, the check-in desk put my partner’s pre-check number in about six times before realizing that it didn’t matter he wasn’t going to get pre-check that flight. It didn’t turn out to be a problem,

Of course, the best part was we get to the screening are and the pre-check was closed so I even though k
I fix have pre-check, I had to go through the regular screening and no they didn’t give me the little card like they were supposed to, but I don’t really care

following up on my original post regarding my PreCheck disappearing...
I was pleased today when I received my Email boarding pass for a new fight I am going to take that now shows PreCheck on it...
I hadn't followed up with the airline or TSA .....it was just reinstated....

I understand because it has happened to me. Rarely, but it happens. Paul and Joe are correct in their info for you.

For poster whose boarding pass disappeared from app: screenshot your boarding pass when you first check in. If you use this screenshot instead of app for your boarding pass, then remember to check if your gate has changed since you checked in!