No idea if this is intended behavior or not, but morph targets set in anim BP Initialize Animation event overwrite curves from anim graph. So if you’ve got some animation with curves hooked up to the anim graph, and add a Initialize Animation event that sets the same morph target (as the curves) to a certain value, it will stay fixed at that value forever, even though the Initialize Animation event is only called once.
I could see this would be the case if you set the morph target value in Update Animation (eg. every frame) but it seems pretty weird that this happens with the Initialize Animation event too.