Why would you do missions on this game... No one does missions anymore lmao they stopped being worth the useless rewards since 2014 - the game is 100% PVP now.
And the reason why damage doesn't work on bots (which you're probably the only player on this game even fighting them) - is because Bots have shared functions with players.
In conclusion, don't fight bots while using God Mode. you're wasting your time for a reward that is miniscule