Have animation controller hooked up, with blend tree, but only idle animation works...

Hi all,
I'm a total newb with Unity. I have managed to get my 3D character (I'm using Sinty's Polygon Knight's pack) to move around using WASD. So I thought I'd download some free animations (Kevin Igliesias' Basic animations Pack. Has walk, run, sprint animations) and hook them up to my Polygon Knight using a blend tree. My BT is set up as per attached screenshot. Notice that the model in the preview is Kevin's model and not the Polygon model. Is that an issue, if so how to I get the preview to show my model animating during the blending testing? Anyway, that is a minor issue and not the real reason for this post.

So, If I select individual animations (BasicMotions@Walk01) then I get this...

But If I select my HumanoidAnimationController, which as you see in the screenshot, contains all the basic animations, I just get the character in IDLE state, moving around.

How can I debug this situation to find the fail point? I presume it is inside HumanoidAnimationController?
I don't want to spam here with a massively long post, but can add the code from my controller if someone things that would help?

I'm using Unity 2019.3.13f1, if that makes any difference? Or if you need screenshot/video of anything else, let me know


D.