I'm sorry, I don't dig it (Pun intended).
Disappearing rocks are disappointing ( I mean, it's not even about "I should not dig for too long, because rocks will disappear and I won't be able to collect them", because if a rock falls further - you won't be able to collect it even if you go after it straight away. Or at least so it seemed. Then you introduce move speed, to kind of make it make sense, but then it becomes irrelevant when you upgrade those collecting platforms.
Also, yeah. Start is totally frustrating... I dig but I can't collect sh*t)
I believe next time you will definitely do better <3