I've been trying D-pad inputs with jump like the initial block by the dragon but I've yet to once get this block to break. Any tips or advice one is supposed to get it to break?

And I just got it!

Anyone else struggling - Hold the Jump button as you're falling onto the ladder then you can just press right on d-pad to break the boulder.

Yes! Anytime you want to use the mattock, the jump button needs to be held down. Same with the use of the Glove from Xemn and the crossbow for Mayna