So, no matter wich cave you go but the crystal caves are bugged.
For example the crystal cave next to unnamed city eith imps.
You hit a crystal, you get crystal once.
Than the crystal stays, so you grab it by hand. (sometimes you get something, but alot of the time you dont get anything.)
If you keep trying to hit it with a pickaxes, nothing happens.
Pre update the cave gave 15k-20k crystal with a starmetal tool.
Now after the update i did get 3418 from that whole cave.