Base reward isn't guaranteed for your entire life. You have to make a decent wager in every month with deposits to be eligible for the base reward. If you reach platinum 1 rank within a few weeks/months wagering activity and expect the base reward in every month then forget about it. You aren't making a decent wager at Stake since last few months. Therefore, you aren't eligible for the base reward of your rank now. Your monthly bonus will go down more if you don't increase your gambling activity at Stake.