Your probes need to be mapped. mQ does not intrinsically know what part of the air conditioner or refrigeration system that your probes are connected to. So, you need to tell it which probe to reference for specific measurements (ie. low side pressure, suction line temp, return air temp, etc.).

Go to the Toolbox, open the list for the respective brand of tool, tap the probe that's not transmitting and select the function from the pop up menu.

For guidance on which probes to assign to each measurement point, see Proper Wireless Probe Placement for Accurate Diagnostics.