I'm using Metricbeat for system metrics, but every now and then system.filesystem.used.pct returns 0% for 24hrs from midnight, but only when being visualised. This happens whether I use Kibana or 3rd party Grafana. If I query for documents using "Discover", then those documents covering the midnight boundary are non-zero.
My indexes for Metricbeat are created daily, and it seems too much of a coincidence that the data would be missing for precisely the length of an index. To make matters even more confusing, the same indexes visualise information on CPU and memory usage perfectly, whilst the filesystem.used.pct is 0!