Apparently AD/DNS running on Windows 2012r2 and AD/DNS running on Windows 2016/19 don't contain all the same counters. I found 18 counters between the two applications that didn't exist in Windows 2012r2 but did in 2016/19. I've created a secondary nri-perfmon config file specifically for those systems running 2012r2 and its working now, though with the missing counters. This might be something good to note on the nri-perfmon integration as an FYI.
Apparently AD/DNS running on Windows 2012r2 and AD/DNS running on Windows 2016/19 don't contain all the same counters. I found 18 counters between the two applications that didn't exist in Windows 2012r2 but did in 2016/19. I've created a secondary nri-perfmon config file specifically for those systems running 2012r2 and its working now, though with the missing counters. This might be something good to note on the nri-perfmon integration as an FYI.