Strange CC7 issue

In two of 21 Rackspaces, Midi Input DSI REV2 (CH2) don’t receive CC7 (Volume) from expression pedal connected to DSI Rev II. That two rackspaces have each two Midi Ins from Roland A88 (CH1) with split settings (picture Rackspace 4 + pict. Rackspace 18).

In all other Rackspaces there are only one Midi In Roland A88 and Midi In DSI REV2 (pict Rackspace 1). In that 19 Rackspaces, Midi In DSI REV2 receive CC7.

What do you see in Window => Show Midi Assignments
in the problematic rackspaces?

Ok, so the midi CC 7 is not assigned to a widget.
What does the global midi monitor show when the CC7 is not recognized in the problematic Rackspace?

In the problematic Rackspace can you midi learn a widget, just to test if this CC 7 is recognized at all?

Global monitor shows CC7 in problematic rackspaces.
Midi learn a widget with CC7 is possible.

So what is the issue with CC 7?
Do you control the volume of VB3 with CC7?

I generally work with widgets and gain assigned to incoming Midi Message.

Huh? According to that MIDI Assignment list, Controller 7 on MIDI channel 2 is in fact assigned to a Widget called Gain.
If you open the global MIDI monitor and move your expression pedal, what does it show?

Yes – as a general rule, you should use host automation rather than MIDI messages to control parameters. Also, when it comes to controlling volume, unless there is a very specific need, you should not control the volume of the plugin itself, instead you should use a GP Gain control (or the GP Mixer plugin) and control volume though that.

Thanks for your explanations.
I was wondering why in 19 rackspaces the volume control cc7 worked without widget assignment, and in two rackspaces not.