Issue happens with Animator Controller Layers & Timeline Track Layers.
This is only repro with Humanoid.
This only happens when BOTH Humanoid & Transform masks are defined in the same Mask.
When only the Humanoid Mask is defined, everything is evaluated as expected.
When both are defined, the resulting RM is incorrect.

repro:
- open RM_controller scene
- play... notice that the Sprint motion is playing on the lower body including RM (expected result)
- select DefaultMale and open Animator window
- select the Sprint Layer, open option gear and replace "MaleMask" with "MaleMask_withTransforms"
note: this is the same Humanoid Mask, but also has a Transform definition
- play...
bug: notice that the Sprint motion is playing on the lower body BUT the RM is from the Walk clip, not the expected Sprint clip.
expected: RM is applied from the Sprint clip.

Although the Transform part of the Mask should not affect the RM of the Humanoid mask, it does. The two Masks in the project "should" give the same result on a Humanoid character.

The "RM_Timeline" scene reproduces the same issue on Timeline tracks.