Putting GE aside. I've never had it and been Pre-Check eligible since the start.

Like several people who have posted, my name was correct on my profile and my ticket NEVER matched because DL pushes my first and middle names together. Up until suddenly a couple weeks ago, it also NEVER affected my TSA Pre-Check status.

Then...

Like many others have experienced, suddenly it stopped working. I had made no changes, purchased the tickets as I always did, and believe my data was completed correctly. (A coworker thinks that was the issue, but I don't.)

DL had to go in and fiddle around with my name. Once that was done, it started to work again.

I was in the same position as you: thinking others must have done something wrong and not understanding how the system stopped working correctly for those people. Then, out of nowhere, it happened to me, so now I understand what those people were talking about.

I did nothing different than I had done for hundreds of flights for which I got Pre-Check. Suddenly, I was no longer Pre-Check eligible for any flights. It didn't print out my boarding pass, nor did I get three beeps. Obviously, something happened on the DL side where my name, even though it looked the same as it always had on the site, took on some characteristic which made me inelegible.

If it hasn't happened to you yet, it's likely going to happen at some point. It's happened to enough people that it's obviously some flaw in the DL programing. Getting DL to re-enter your name into the Secure Data system seems to be the fix, even when the name reverts to exactly how it appeared before. It seems every week or so a new thread pops up here with a mystified OP who thinks he/she is the first one to ever have this happen.

The issues people have with GE and trusted traveler numbers is completely different from the issue concerning those of us who, like you, had no issues and no changes yet suddenly saw our Pre-Check eligibility disappear.