Marionette Hopeless
Having seen the incredible potential of Marionette, I've spent a tremendous amount of time with it. But it's been one issue after another. I realize I'm on a steep learning curve, and certainly plenty of my issues can be attributed to that, but, I'm pretty sure a disproportionate amount of them are due to the bugginess and general dysfunctionalism of Marionette. Among other things, I'd had high hopes for Marionette as a way to overcome some of the bugginess and general dysfunctionalism of Vec
This can sometimes happen if you choose a texture that isn't already in your document. The list of textures gets reordered which can change where the object is looking for the texture, that's why on your next attempt the texture updates correctly.
Right now there's not a good way to get around this if you're using that node, other than always selecting textures at the top of the list (the ones that already exist in your document)