Idk if watching smth by way of mst3k counts but Monster A Go-Go (1965) has literally no resolution to its plot, the titular monster has like three mins of screentime before vanishing without a trace right before it gets caught (the episode itself is a personal fave of mine though)
MST3K had that one that had a very long title like "the attack of the guys that died and became mixed up monsters" and between that and "the Wild World of Batwoman" those are probably even worse than Monster A Go-Go. The latter was just a bunch of framed women sitting around doing fucking nothing.