Don’t know what you mean by “sketchy” and I don’t know a thing about DeltaQ chargers but I know that if the pack voltage is below a certain level (65V?), some chargers won’t engage and charge the pack. Maybe that is your problem?
Solution is to use a standard 12v car charger on each battery individually until they are all charged sufficiently and the entire pack is above the onboard chargers cutoff point. Might be worth a shot.