Problems with in ear monitor

Hi everyone on the forum, I have a CQ20B that I use with the band, we are six elements and therefore we use all six aux outputs to independently adjust our in ear monitors via six CQ4You apps, apart from the six personal devices we also have an iPad to control the CQ20B with CQ-Mixpad. The problem we have is this: it often happens that in CQ4You a channel (for example the panoramic microphones of the drums) enter the same channel as the keyboards so it becomes impossible to lower the panoramics without having to lower the keyboards too, this can happen with different channels in each aux output. It also happened to record in multi track and during the re-listening phase the guitar came out in the same channel as the voice. Could it depend on too many devices connected? (it should support up to 6 + 2) or did I not understand something and is there some wrong setting? or is the mixer damaged? or maybe it is a common problem? I thank all those who want to give me their opinion.