The following code is not being evaluated at all
@variables ξ
u_h = [1, ξ]
γ_matrix = rand(ComplexF64, (2,2))
foo = eval.(build_function.(γ_matrix*u_h, ξ))
foo[1](0.) # 0.718261200283448 + 0.7541320221601713ξ + im*(0.11955519784649504 + 0.6025851857044455ξ)
No idea what is going on ):