Maximum number of audio tracks is ONLY 5? - And what is the purpose of the mix tracK?

Hello,

I am trying to add an audio to a SIXTH audio track manually,

But I can't, the cursor (which we cannot see in the screenshot) shows a hand with a "cancel" button, indicating the impossibility to add the audio BELOW A5,

I was expecting to drag the audio below A5 and be able to create A6, like I did with A4 and A5, but it does not seem to work that way?

The audio I want to add would always fall on the last track (see the screenshot) OR if I move it below A5 too much, it will do nothing (hand with a cancel button cursor).

Why are we restricted by this number?

While writing this post, I noticed the mix track, I wonder if this can help, what does it do anyway?

Than,ks