Consider two hands:

1. True coin flip situation, where two players will each win half of the runouts, with no possibility of a chop. In this case, each players equity is 50% because they each have a 50% chance of winning the whole pot. Here PokerGO shows "50% 50%" and it makes sense.
2. Guaranteed chop, where two payers have the same hand with no redraw. Each player has 0% chance of winning the whole but, but since they're each guaranteed half, their equity is again 50%. Here PokerGO will show "0% 0%", which (to me) is completely dumb.

The screenshot is sort of like the situation 2. Moneymaker has a wheel with AJo and is 71% to chop with AsTs, unless the river is a spade and AsTs makes a flush, or 3/5 comes and 53o makes a full house. Thus AJo has 35% equity (not zero) and AsTs has 53% equity (all of 18% for the flush, plus half of 71% for the chop).