This seems to be a rules error, but not for the reason you think. There are three rules here:
- no 6's and 8's adjacent to each other
- take numbers from tiles adjacent to your own cities and settlements
- no settlement or city shall be left barren.
These rules can be broken in order from 1 to 3, meaning that rule number 1 is the first rule you can break, and rule 3 is the last rule you can break. So the 6's and 8's aren't as big a deal, it's the fact that there's settlements without any resources that's the real problem here.