Online, it said it couldn’t verify my passport information when checking in. Also, when I tried to scan my passport to print my bag tag at the kiosk, it said the names didn’t match, and someone had to manually check my passport when getting on the flight after trying to scan it. I assumed it was the missing space, though it could also be that my ticket was missing “II” after my name, which my passport has.
Thats's normal in how names are shown on airline tickets - spaces are removed. It should not have caused any issues. Did you actually have a problem checking-in on-line or at a kiosk or did you just assume there would be a problem and went to check-in agent?
The "names must match exactly" is not completely true as it appears to be somewhat of a fuzzy match. I'm retired from an airline so our names on our flight benefit tickets come from the employee database and are just full first concatenated to middle initial (no full middle). Despite that, I am 100% at getting Pre-Check since getting Global Entry even though my passport (and therefore GE card) is FIRST (full)MIDDLE. Never a problem (the only "problem" is my son is Brian A which shows up on tickets as BRIANA which has caused some people to look for a girl). In fact, we flew WestJet (we get benefits on other airlines as well) just a few months ago and no problem checking-in on-line with our names as FIRSTM.