Thats actually how I've been getting up there... although I've tried doing it with both bombs and just the spring ball (eventually realized springing was faster and easier to control) ... the result is the same despite the method though (that... block on top)... back to trying.
I know what you mean. They placed an invisible block on top of the track. You can bsj onto it but once you go in morphball your actually higher than the whole and can't go in. This really, really sucks. I haven't tested but it probably goes away once you get spider ball.