Last/current data point in Grafana showing up as null

I have two Ubuntu machines that are configured to receive telegraf data and add it into an influxdb database. For some reason, front time to time, the machines would show the last entry on some of the data (like memory usage) as null. This happens at random and sometimes all data points would show, while sometimes they won’t. If I use a visualization such as a gauge, the would be blank for awhile until it receives a good data point (when set to show the latest/current).

I’ve checked the machines and they’re all configured to the same time and time zone (and get data off the same NTP server).

Here’s a screenshot of the setup: