I've found that OnBeginDrag, OnDrag, and OnEndDrag are all called like normal, in this situation, but OnDrop is ignored. So far, I've only tested it with the OnPointerClick event in a separate monobehaviour on the same GameObject (which had an Image component attached to it, to catch the events). This seems like a bug, since I wouldn't expect two, different events to override each other. If anything, this would only make sense if both events relied on the same basal event (like OnRelease), but even then, it's a bit perplexing why they override each other, since the criteria for calling them don't overlap. If OnPointerClick succeeds, it means you didn't drag the pointer far enough to start a drag event. If OnDrop succeeds, it means you moved your pointer far enough to start a drag event, which is too far for OnPointerClick to succeed from.