AR Overbridge. Different levels on Main and Instrument

Hello!

I use Ableton with AR. I found that signal on main AR channel (outputs 1-2) is lower than signal on AR instrument. On the attached screenshot you can see -4.13 on outputs 1-2 and 0 on output 1.
Compressor “Mix” is set to 0, so it is not a reason
Any ideas, why it is like this?

Many thanks!