MainStage volume mixing vs Logic

Hi friends,

I have been working in Logic Pro X for studio work and then running a MainStage rig for our live shows. Both latest versions (Logic 10.3.2 & MainStage 3.3.2)

However, I keep running into this issue:

1. I have a song mixed perfectly in Logic, with Software Instruments (recorded with an AKAI MPK 249 MIDI keyboard) level-set against analog recordings for guitars & vocals.
   
2. I re-create the same exact Software Instruments with the same volume settings, plugin settings, Sends channels, etc. in MainStage as I had in Logic.
   
3. I then re-create the same exact analog channels for guitars / mics / etc. with same exact plugin settings, Sends channels, etc. in MainStage as was in Logic.
   
4. When we go ahead and try to play live in MainStage, the volume is all over the place.

Am I missing something obvious? I initially thought it had to do with MIDI velocity sensitivity, but I'm using the same exact MIDI controller with the same exact settings for both Logic and MainStage. I always have to essentially re-level set and re-mix in MainStage all over again, even though I've done it once in Logic already. Super annoying.

Please help! Any & all advice appreciated!