Both the presidential map and the Senate map on https://manifold.markets/election have the pointer at the top, which is meant to point to the the location that would represent a 50-50 split in the Senate or Electoral College. However, this pointer is in the wrong place in both cases - it's slightly to the right of where it should be in the presidential map (hard to see now, but it was obvious when Nevada was placed to the right of Pennsylvania, because the pointer pointed to NV as the tipping-point state when it should have pointed to PA). On the other hand, it's two seats to the left of where it should be on the Senate map, though this is balanced out by the fact that the map places Maine and Vermont on the right due to them being (nominal) Independent vs. Republican races.
This market resolves YES if, any time before the first polls close on Election Day, Manifold fixes both of these problems with the Senate map. In other words, the "50 to win" pointer must actually point to the middle Senate race, and the races should be put in a more reasonable order (presumably using the same algorithm that determines their colors).