Inspired by the recent progress of acceptor-donor-acceptor (A-D-A) type non-fullerene acceptors (NFAs) with easily tunable molecular structures and strong near-infrared (NIR) absorption, the Organic photovoltaic (OPV) cells achieved great progress in power conversion efficiencies (PCEs), especially ternary OPVs. The ternary OPVs with two different NFAs and a polymer donor have resulted in a record efficiency for a single-junction opaque OPV cell with PCE of 19.6% and a semitransparent cell with PCE of 11.4% and 47% visible transparency. Unfortunately, their ability to withstand use in adverse environments over long periods is, as yet largely unproven, and the causes of instability are not well understood. In addition, high reproducibility of ternary solar cells has yet to be achieved in the ternary NFA-based cells. In this work, we find that almost all the non-fullerene acceptors (NFAs) used in high efficiency ternary organic photovoltaic cells undergo reactions during blending that create a plethora of reaction products. Briefly, if two NFAs are blended in a solution at elevated temperature, the acceptor end groups exchange between the molecules, creating at times up to 6 different NFA molecules within the bulk heterojunction mixture. These reaction products are dipolar, leading to a decrease in charge extraction efficiency, changes in film morphology and in the photogeneration dynamics. This unanticipated result has significant impacts on ternary OPV performance, reliability and reproducibility.