TargetableDrones is not compatible with the paid plugin known as BetterNpc, these NPCs will not be aware nor shoot at the drone. 

Thanks for reporting. The NPC feature is brand new and I anticipated that it might not work with some of the NPC plugins. I'll troubleshoot this compatibility issue in the next few weeks.

glad to help!

I looked into it. It seems that the NpcSpawn plugin spams errors. The root cause is that NpcSpawn isn't coded to be able to target non-player entities. I contacted kpuctajl about this issue to see if they will fix it.

An update was released for NpcSpawn that makes it compatible. Please let me know whether that has resolved the issue for you.

WhiteThunder

An update was released for NpcSpawn that makes it compatible. Please let me know whether that has resolved the issue for you.

i can confirm this now works like a charm.