A4 controlling track volume by midi

Okay… I’m not sure if this is an A4 topic or a machinedrum topic, but here goes. I would like to control the volume of each synth track with my machinedrum. I do this by making 4 midi machines to control track 1 through 4. I assign the 1st cc knob to control cc7 (amp volume), and I use a control 8P machine assigned to each of the knobs that would send midi information to control volume. What I find, is the connection often gets broken, ie synth 4 all of the sudden won’t receive the cc volume information sent by the machinedrum, and sometimes it does… I have no idea why this is the case. The reason I want to do this is I often control synth levels while muting sounds on the MDUW, thus I need my hands close. The program change information seems to work well, the sync works well, I can program midi notes from the MDUW into the A4, but I cannot get consistent results with the CC assignments. f anyone has any tips/advice it would be much appreciated.