Users of TuneLab for Android noticed that on a few Android devices, notably the LG-G3 phone, there were always two peaks in the Spectrum Display when tuning the note B7, as shown here:
When this happens, it also makes the Phase Display unusable, making it impossible to tune B7, even though every other note tunes just fine. It turns out that on these phones, the normal audio configuration uses a form of noise-cancelling that introduces "ghost frequencies" around 4,000 Hz, which is right around the pitch of B7. We found that enabling an alternate form of audio configuration in TuneLab fixed this problem in the LG-G3 phone. But this configuration change was not optimal in other phones that did not have this problem.
To address this issue we offer two different audio configurations - one for those devices that have the "B7 problem" and another for all other devices. In order to make both of these configurations available in the same download of the software, we added an "Advanced" setting button on the "About this Version" page in the software. If your device exhibits the B7 problem, go to "About this Version", tap on "Advanced", and change select the alternate audio configuration.