Hello, I might not be expert, but I am trying to help you.
How you’re doing:
I believe you using DefaultSlots before leg and foot IK logic. What will happen on that case, is first the montage on DefaultSlot will actually be applied. But afterwards, leg and foot Ik will use arms and legs from the played montage pose to respective ik pose.
Here’s what it looks like:
You see I applied montage using Default. This pic is different from the subject. But consider them as montage and IK. Now IK takes the hands from montage and change their usual montage position and rotation.
How to play montage on top of hand and foot ik:
Here’s what to do. You don’t turn off and on anything. Instead, play montage on top of those IK. First apply IK. Than take your Montage Right and connect IK Output to Montage Input.
What will happen is even though, IK isn’t turnt off, the IK will be applied first. And than the montage will replace it’s pose on top of the IK pose. It is how it’s meant to use I believe. Expensive, but it’s what I do.
And I assume you have default slot on your montage after finished writing an answer. I don’t know if you came up with any solution since you have no response so far yet.