I recently traded in my Ford and despite immaculately maintained DIY records input into mycarfax, none of them showed up when they ran it.
Funny thing is, because that car had a ton of safety recalls and warranty repairs it looked like the car was “serviced” by the dealer every 5K miles or so. The dealer never changed the oil or did any preventative maintenance but Carfax came back with the “Dealer Maintained” label on the summary page, again because of how unreliable it was.
Because they don’t actually list our DIY entries when someone runs a report, I’ve stopped using the Carfax app and don’t bother reporting my DIY maintenance anymore. I just use the Notes app on my iPhone; it is synced with my iCloud so I know that I’ll never lose the records.