Mathematica can't simplify disguised expression [duplicate]

Question

When I simplify the following quartic polynomial with a linear constraint;

Simplify[x y z a + x y z b , a + b + c == 0] // Expand

I get what to me seems like the most simple form

-c x y z

Now I disguise the problem a little;

Simplify[Subscript[k, 1]\[CircleDot]Subscript[k, 3] Subscript[k, 2]\[CircleDot]Subscript[\[Epsilon], 3] Subscript[k, 2]\[CircleDot]Subscript[\[Epsilon], 4] Subscript[\[Epsilon], 1]\[CircleDot]Subscript[\[Epsilon], 2] + Subscript[k, 1]\[CircleDot]Subscript[k, 3] Subscript[k, 2]\[CircleDot]Subscript[\[Epsilon], 3] Subscript[k, 3]\[CircleDot]Subscript[\[Epsilon], 4] Subscript[\[Epsilon], 1]\[CircleDot]Subscript[\[Epsilon], 2], Subscript[k, 2]\[CircleDot]Subscript[\[Epsilon], 4] + Subscript[k, 3]\[CircleDot]Subscript[\[Epsilon], 4] + Subscript[k, 1]\[CircleDot]Subscript[\[Epsilon], 4] == 0] // Expand

And Mathematica no longer makes any simplification, I just get out what I put in

Subscript[k, 1]\[CircleDot]Subscript[k, 3] Subscript[k, 2]\[CircleDot]Subscript[\[Epsilon], 3] Subscript[k, 2]\[CircleDot]Subscript[\[Epsilon], 4] Subscript[\[Epsilon], 1]\[CircleDot]Subscript[\[Epsilon], 2] + Subscript[k, 1]\[CircleDot]Subscript[k, 3] Subscript[k, 2]\[CircleDot]Subscript[\[Epsilon], 3] Subscript[k, 3]\[CircleDot]Subscript[\[Epsilon], 4] Subscript[\[Epsilon], 1]\[CircleDot]Subscript[\[Epsilon], 2]

I do have some rules defined for \[CircleDot] which make it like an inner product, but I don't think that should affect this situation.

To me, I have asked Mathematica to do exactly the same thing twice. Why can it not do it the second time?