Getting "No data" instead of Displaying Valid 0s (zeros)

Hi,

I have a MySQL replica syncing data from a MySQL master. Most of the time the replica is up to date (sync latency = 0 seconds), but sometimes the replica falls behind master by couple of seconds. I want to graph this sync latency.

I get the data from CheckMK data source. The data source works, the Query Inspector sees this series of 60 values (1 hour worth of data sampled every minute):

{"result": {"step": 60, "start_time": 1605594720, "end_time": 1605598380, "curves": [{"color": "#ffb080", "title": "Sync latency", "line_type": "area", "rrddata": [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1.63333, 0.666667, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]}]}, "result_code": 0}

For these values Graphana shows this graph:

Where are the zeros? Why doesn’t Graphana show them as aline on x axis? Even worse, then I have a time period with zeros only (slave was up-to-date all the time) the graph shows “No data”.

How can I configure the graph to show the zeros?

Thank you,
Regards,
Oskar