With DynamicPolynomials and non-commutative variables, (x+y)*z does not work

How to right-multiply x+y by z in DynamicPolynomials when x, y, z are non-commutative? I have tried (x+y)*z, but Julia returns an ERROR: MethodError: no method matching map_exponents(::typeof(+), ::MonomialVector{…}, ::Variable{…}) Strangely, z*(x+y) yields the result zy + zx properly. The documentation for DynamicPolynomials is terse and it does not indicate anything special about right-multiplication by a single variable.