Animation Montage breaks Anim Graph flow - video attached

I am creating a turn based rpg style game. For my characters difference poses and transitions I use an anim graph, organized in such a way where the different stances are controlled by boolans set on the Characters Blue Print (as you will see in the video).

This seems to be working quite well, but when I execute an animation montage(around the 16s mark in the video), the anim graph seems to reset resulting in an awkward result where the character is trying to catch up where it should be.

Video here

Does anyone have any idea why this is the case, and how I can remove this or work around the issue?

Thanks,