#The Problem
The gesture layer has an issue where only the mask from the first layer is used, if I make another mask for layer 2, it will still use the first one. This has to be vrchat related since you can use different masks like that in Unity itself.
#Why its limiting
Sadly this will limit controlling your avatar in interesting ways.
#Recreation Steps
  1. Create Animator for "Gesture Layer"
  2. Add Second layer inside the animator
  3. Set weight of the created layer to 1
  4. Create 2 different "Avatar Masks"
  5. Give both masks different masking settings (example: legs on one, arms on second)
  6. Make 2 different buttons to trigger an animation playing on the 2 different animation layers
  7. Whatever is on layer 1 will work fine, layer 2 will use the mask from layer 1
#Video Example
It shows unity setup, masks and examples and 2 avatars showing its related to layer order: https://www.youtube.com/watch?v=2dgg9qYCwd4