Investproxy.com administration provided an explanation for the reason of delayed payouts. According to their update this problem was caused by technical issues:
We had a slight issue on Saturday with our script and since it happened during the weekend we were not able to immediately rectify the it. However, we are glad to announce that the problem has now been taken care of.
Please note that we are working to clear any pending cashouts. Be informed that every cashouts will be cleared within the shortest time.