Why can't I move an anchor point when the layer has a motion path?

[G Alder]

I'm moving 7 balls to a circle, then want them to rotate around the circle. When I try to move the anchor point with the Pan Behind tool, it changes the motion path. When I try to change the anchor point in the timeline (using the numbers), it moves the object. If I delete the motion path, I can move the anchor point (which is way off to the side of the layer's beginning position), but then when I start a motion path, the anchor point moves as well, and I have to move it back. Keyframing the anchor point at the point on the timeline where I want the balls to rotate has no effect on this. I have Show Layer Controls checked in the View menu.

I spent a while doing the motion paths; I don't want to have to delete them to get this to work, and it seems awkward to have to move the anchor point at the beginning of the animation, before I create any motion paths. Is there a workaround for this? I can't believe a simple animation like this would be so difficult.

Any help anyone can give would be greatly appreciated.

[Mylenium]

Based on your description there is nothing wrong with AE, your workflow is just terrible, no offense. Nobody in their right mind would even want to move the anchor point throughout an anaimation or animate it, which is of course possible. That's what parenting is for and from your words it sounds like you may want exactly that - a Null in the center of the circle with your balls parented to it while the Null rotates. that and of course people split up stuff in multiple steps/ temporal segments by splitting layers. Again nothing to do with AE, just how one would approach animation in general to not cause a mess. You have a segment with your balls rotating around the Null (or alternatively the whole thing being a pre-comp based layer that simply rotates) and then a second segment where the balls are animated freely with conventional keyframes as they move into their ring positions. You know, it's all an illusion. There's no point trying to do this in a single sweep and how it would be in the real world.

Mylenium

[Kyle Hamrick]

An important perspective that may help the way you think about this: 
A layer's Position is actually the position of the layer's Anchor Point in composition space. 
This becomes clear here, where the apparent visual position of this 400x400 solid doesn't change, despite the Anchor Point and Position values being very different. 

This also may help give you insight into why these values change when you parent a layer to another; in that case, Position is now the position of the layer's Anchor Point in the parent layer's layer space.

Mylenium tends to be a bit undiplomatic, but he's right that parenting and nulls are probably the most straightforward solution to what you're describing. 

For your specific situation, I'd probably create a Null, cut/paste the Postiion keyframes you've already created onto that, then parent your existing layer(s) to this Null. Now you'll have the ability to move along that motion path, but also make other adjustments to your layer (changing Anchor Point if needed for Scale or Rotation purposes, for example) as needed.

If you need a little guidance on working with Nulls & Parenting, hopefully this can help get you started: https://www.youtube.com/watch?v=TP1fEnJkzmQ

[G Alder]

Here's my problem with using a null object, one I didn't mention, and that was my omission: the balls need to rotate out of the circle, and if I use a null object, once they're parented, I can't do that.

Mylenium is right that splitting the layer might be the right approach (which is funny, because I just did that for a different project and it absolutely didn't occur to me), and yes, my workflow is terrible because I'm just starting with AE after years and years with Illustrator and Photoshop (I'm just over halfway in a course on it--just enough to dangerous and whiny (-; ).

Thanks to both of you for your help. I really do appreciate it.

[Kyle Hamrick]

Sometimes complicated moves involve a bit of setup time, and a bit of trial and error! 
I've definitely built rigs in the past with a central null that rotates everything, and then each piece around that central null has its own null, and then the actual objects parented to those nulls have their own keyframes as well ... 

It's also possible that what you're building might benefit from some simple expressions work? If you're able to post screenshots or work-in-progress of what you're trying to achieve, we might be able to make some suggestions about the right way to structure your project. 

[G Alder]

I'm just now learning expressions. I'm not a coder, but I'm getting by. Thanks for your suggestion!