Not sure that normalize is working when nodenames are specified

[mathlawguy]

I apologize if this is user error, as I am pretty new to Julia. When I use normalize with just the factor itself, the function performs as expected.

normalize(Factor([:a, :b], Float64[1 2; 3 4]))

But when I ask it to normalize with respect to a dimension, I get a MethodError.

normalize(Factor([:a, :b], Float64[1 2; 3 4]),:b)

MethodError: no method matching sum(::typeof(abs), ::Matrix{Float64}, ::Vector{Union{Nothing, Int64}})
Closest candidates are:
sum(::Any, ::AbstractArray; dims, kw...) at reducedim.jl:874

Am I doing something wrong or is there a bug?