It should be fixed now, I do apologize(I an genuinely sorry. I bug-test all my stuff thoroughly but I could not have done testing that anticipated 300+ players in the level, which is what caused the issue). On serverside the shovel will not dig when there is a wall, and despite the level being singleplayer(which is similar to an instance) on serverside players still were counting as blocking/walls. This is not something I anticipated, so the shovel was simply refusing to dig because there were so many players it was all considered a giant wall.
TL;DR I apologize and it should be fixed. When I got off last night not that many players had discovered the cave so the issue wasn't all that prevalent.