This is very similar to #855, but I'm not sure if it counts as the same thing. Having the same problem mentioned in that ticket, I did a little testing with the flags "meta-autoset" and "single-use". I a few test fields where the intent is to not have a block drop yet no method seems to work.

First I tried your suggestion from the previous ticket and excluded the "meta-autoset" flag:

- title: Dummy
  required-permission: preciousstones.dummy
  meta-name: '&bDummy Field'
  meta-lore:
  - '&7This is for testing'
  block: 170
  radius: 10
  cuboid: true
  welcome-message: true
  farewell-message: true

When the above field still dropped a block on break (Even for a player in creative), I tried adding the "single-use" flag instead. This version also dropped the block when the field was broken. To be clear, I am using the above block as it was given to me via the "/ps give" command, not a normal un-named block of the same type.