Drop last bucket not working

I am seeing a lot of zero values using metricbeat, causing readings to be wrong. I have "drop last bucket" selected on the visualization, but it doesn't seem to be working correctly. That feature is supposed to eliminate this issue, right? In the screenshots, you can see one sample where the data is good, and another where multiple hosts report zero for the last sample.

Is it possible the last two buckets are empty for those hosts?

The last bucket probably is, yes, but that's the purpose of the feature "drop last bucket", right? They are all synced with an NTP server, and I verified that they all have the same time showing. This is all data from Metricbeat.

Yep, that's why I'm wondering if both the last and second to last buckets might be empty for those hosts. It's difficult to debug TSVB visualizations themselves, but you could create a basic Kibana vis with a date histogram on the x-axis with the same time interval (10 seconds from looking at the screenshot) and a sub-bucket with a terms agg on the hosts field. Then you could see the values for the individual buckets. On regular kibana visualizations you can even click the gear icon on their dashboard panel and click "Inspect" to see the underlying data coming back.