Bug/Spot to dig that actually is impossible to dig

That's inside Luculla's Mines, it's a secret spot but it's just impossible to dig! Have anyone been able to dig it?

http://cloud-4.steampowered.com/ugc/540751909801607020/7128FC7CFBA0C2220FE9D737EDD2F5972BE05BB1/

same problem but only different location= x:284, y:98. (happened even before patch .132)