Many (artificial) potential Sources at 0°, +-90°, +-180° Longitude

[Slothologist]

Hi Guys,
after setting up our 8SoundsUSB + ManyEars with a slightly modified config file (basically the johnny0.mes from the Experiment folder, fittet for our roughly 20x20x20cm cube) we get a number of very strange potential sources at circa 0°, +-90°, +-180° Longitude, even in a very quiet room. Please take a look yourself:

Actual sources are often visible as well, but very faint. Thus most of the time, the actual sources we want to find are not tracked. We already checked the hardware, at least in Praat all the microphones seem to record correctly. Could you help us resolve this error?
Thank you very much for your help :)

PS: Our config file:
rect_cube.txt