It looks to me like, the OnBeginOverlap is working correctly, it will fire exactly one time, per “contact”.
Two objects A and B, both set to generate overlap events, like you have them set up, or it wouldn’t work at all.
When either A or B, contacts each other, the event will be fired, as soon as A or B, exit the overlap “area”, then the event becomes “re-armed” again, to fire, should A or B contact.
To keep something going on continuously, you need to remember, the overlap event, and then turn off remembering when you get an OverlapEnd event, or that A or B check per tick (or some interval), with a Get AllOverlappngActors node, and the equivalent for Components if you care about that.
Just a thought, have a great day!