Total Traffic alerts are not working

For some inexplicable reason I can't get Total Traffic alerts to be detected.

I tried a very simple setup just to confirm that my total traffic alerts would be triggered.

So I created an alert that would be triggered if total traffic decreased by 1% when compared to the previous hour.

And another alert that would be triggered if total traffic increased by 1% where compared to the previous hour.

As can be observed in the following chart, traffic does swing back and forth exceeding the 1% threshold.

I can get alerts if I use anomaly or any other metric such as rate of 5xx errors.

But total traffic seems to be broken.