Alpha 18: checks/alerts not triggering?

I’ve noticed that the Monitoring/Alerts History page occasionally shows some of my checks just stop being shown altogether.

For example, I have 4 identical checks (cloned, but given different names and slightly different offsets), but only 1 seems to be triggering and writing out stuff to _monitoring. The rest, though enabled, don’t seem to be doing anything.

I can’t find anything in the logs that seem to show anything that would help.

Found one issue — it seems like some template variables (such as ${r._field} and ${string(v: r._value)} were causing execution errors, preventing the checks from working properly.

Now, the only thing I’m noticing is that in one check, I get N results (where I have N hosts), but for the other similar check, I get a subset M hosts (where N > M).