Condo board says cant charge late fees to delinquent owner

Our New York condominium building has an owner who is seriously in arrears on multiple apartments. Since the early days he was in arrears he has not been charged any of the regular late fees (as specified in the building rules) that are charged to all owners. The Board is now saying that this is because there is a prohibition against charging them once legal action has been commenced. Can you comment on that and, if there are some limitations on imposing those regular late fees, can you comment on when those limitations apply and how they might be dealt with in any legal actions to try to recover them.