The term "settles up on" typically refers to reaching an agreement or finding common ground. Antonyms for this phrase could include "disagreeing on," "opposing," "clashing," "struggling," "diverging," or "fighting," implying a lack of harmony or consensus. When two parties cannot find a middle ground, it can lead to tension or conflict. Other antonyms might include "ignoring," "disregarding," or "avoiding," indicating a lack of interest or concern. Overall, the absence of settling up on something can refer to a failure to reconcile differences or come to a mutual understanding.