Why am I not getting any input signal from the microphone in Reference 4 Measure?

Make sure that your audio interface is connected to your computer and you have selected the correct input from the dropdown menu in the Measure app.

Also, ensure that the +48V phantom power is switched on on your audio interface for your input channel. Most XLR to XLR cables will be able to transmit phantom power but XLR to TRS cables will fail in most cases. Make sure that your cable can supply phantom power to the microphone!