This sounds very specific problem which needs more information. Screenshots or video might help us to understand it better. We need to know how you set the whole thing up.
The cause can be anything. Maybe casting fails, maybe the value isn’t valid, maybe the class does not exists, maybe the function fails to executes, maybe the UI is not in viewport, maybe other class interfere with the execution, maybe execution interruption. It could be anything.
That’s why we need more information to help you.