Why does AcousticSL always return the same angle independent of the data?

[MKiss.1]

Hello, I'm trying to get Acoustic_SL running to detect the sound location with two INMP441 MEMS microphones. Unluckily, Acoustic_SL does only return two angles {-87, 88} independent of the processed PCM values. May anyone have an idea of what might go wrong? Note: I extracted the important code snipped from a larger C++ project to post it on the forum.

Angle estimates independent of the actual sound source.

Some defines and the compression function. The compression throws away some of the MSB bits to gain sensitivity.

DMA callbacks.

Main application.

 

Example of compressed samples with alternating L/R channel.