I have 2018 Bolt and use a Schneider EVlink level 2 charger at home and Chargepoint level 2 charger at work. Most of my charging data from "Charging Stats and History" is there and appears correct. The problem I have is that some charging sessions are not reported. About 10% of my charge sessions are not captured and it can happen for both home and work charges. I can capture missing work sessions on the Chargepoint web site. When they are captured, the Chargepoint and Bolt data agree.
This is clearly a software problem somewhere in the Onstar system. My guess is related to comm failures not being retried/recovered correctly.
Bolt support is of course no help. They want me to take it to the dealer who is also clueless.
Wishlist item: Add the mileage to the charge session info.