It’s really up to the creditor
There’s no requirement for any lender to report anything to the credit bureaus. It’s entirely up to the lender.
I can’t think of any national lender that doesn’t report a repo to the credit bureaus. Not only they report it, it’s very likely that they will go after you for the balance of the loan, including late fees and legal expenses…
That could end up for almost the current loan balance, because the vehicle would be sold for a very small price in an auction.
As to why the loan has not been reported to your credit reports – hard to tell. Will for that reason the repo won’t appear on your reports? Maybe so.
In any case, it’s entirely up to a creditor whether or not to report anything (good or bad) to a credit bureaus. The law only requires for the report to be correct!