Bandwidth scanner graphs are empty

When I open: https://consensus-health.torproject.org/graphs.html#bwauthstatus

I see graphs for fallbacks and running, but the graphs for bandwidth scanners are empty. (They have an axis, but no lines on the graph.)

But the current status text is ok:

maatuska 	6910 Measured values in w lines
bastet 	6837 Measured values in w lines
moria1 	6888 Measured values in w lines
faravahar 	6821 Measured values in w lines