Even with a working miner, you can receive alerts if you set the minimum difficulty for a worker to a significantly higher value than recommended because its communication frequency with the pool will not be optimal. It will lead to high variance of its hash rate (wide range of values in different time periods).

Higher hash rate variance makes proper monitoring more difficult and can lead to false monitoring alarms (you can be notified about some event even when the worker is working correctly).

We recommend to either allow vardiff algorithm to select the difficulty for your worker automatically or set the minimum difficulty provided by the vendor of your device on your own.