Mouse events "disappear"...

When I use a branch in a mouse event, the process disappears without passing through the return node.
In OnMouseMove, I’m trying to change the result depending on whether the mouse is left-clicked while moving. But the result “True” is not output.
PrintString is printed normally before the branch.
If False, the PrintString will be printed only if there is no left click.
However, if True, nothing will be output even if the mouse is left clicked. Nothing is printed either before or after the drag event.
Why? Where did the processing go? By the way, no drag events are fired.