@weibinliu It looks like all of the markers for that sample are filtered out, as indicated by the hollow rings. To include that sample in the calibration calculation, you can do a couple of things:
Capture more samples near that position facing the same to sensors. This will bias the calibrator to include them.
Open up the filters (move them to the right) to make them allow more samples. Be careful, though - opening the filters up too much can result in the inclusion of low-quality samples, which can make the overall calibration worse.
