Change UI outline/shadow via animation

Hey, I'm using UGUI buttons with an animation as transition. With the animator controller I'm able to modify almost all values, except for the UI.Outline script, which does not seem to work properly. Trying to change the effect distance does occasionally work, but most often it will just do nothing, leaving it at the original state. I've even tried the UI.Shadow script with the same outcome. The values in the inspector are displayed properly, the outline is just not changing. If I modify the values through a script however it seems to update properly. In theory I could link up a script with the outline effect to get what I want, but that seems like a terrible hack for a problem that should not really exist.

My question is, has anyone experienced this behavior before? Is it common, will it be fixed? Or am I just missing something obvious here?