now I remember...may be there is a little bug, but the trick is, select again the already selected channel, to get the 'right' channel inserts in the mixer's master section.
You won't see happen anything, but after that the inserts work properly.
I noticed that I saw the choosen insert appear in another channel's insert, this happened more than once.
Reselecting the right track solved the 'bug', with me at least
