You may have noticed that while you can clearly see some APs discovered and listed in NetSpot’s sidebar, you can’t locate the same APs on the heatmap. The most probable reason for that is usually the default AP detection sensitivity value in the heatmap settings. You can open these settings by either clicking the settings menu in the upper right corner of the app window or by clicking on the gradient on the lower right. The particular setting that needs tuning in this case is “AP detection sensitivity“.
By default, you will only see those APs on the heatmap that have a signal equal to or stronger than -50dBm. You may change this using the setting mentioned. If you slide the indicator to the far left position, each and every detected AP will become visible on the map, however, the validity of their positions will be lower, as APs with weaker signals may in fact be located outside the borders of the surveyed area (they may appear on the edge of the heatmap).
The default value of -50dBm was chosen because the majority of APs in real environments have the signal of -40dBm when measured close enough to the AP itself. All lower values are considered to be either outside of the taken sample or belonging to a different floor.