this was brought up before a few times i think. the problem is that the counters that fill the mining/ artifact/ research pools fill the pools with less than the player should be getting occasionally if a planet is currently developing and has not been visited for a while. the only real way to refresh the value is to go to that planet and click though the tabs (my method). i have to do this at least once a day per colony if it is not peaked yet to ensure i am getting all the production from that planet. this may work on already peaked planets as well.