I've run some basic logistic regressions, sampled and not, and with other factors included, the coeficient is significantly negative. As a modeler, anything that doesn't make economic sense, I would generally toss out. Trying to understand if there is a world where this makes sense.
One thing I have come up with is LC's underwriting possibly rejects borrowers with higher delinquencies with a higher probability to default. Those that make it through are better credit risks and have a lower probability to default.