This is a known issue.
We had a bug on rollout that caused some locations to have no dragons. After fixing it, we decided that it was better to re-issue the command to make sure all locations got at least one dragon. The side-effect of this is: some locations will have a second dragon spawn after the first is killed, and the re-issue includes the randomization, so it could be the same dragon or it could be a different one.
For those locations, after the second dragon is killed, everything should return to the normal intended spawn behavior.