PyCall pyimport fails to import python submodules when embedding in C#




We have stumbled upon a puzzling case where we are unable to import python submodules when embedding Julia in C#, e.g.
@pyimport skimage.draw as draw
works just fine in the Julia (0.5) REPL, but gives a null pointer when embedding in C# (using the C-interface via SWIG) - called from jl_eval_string.
pyimport(:skimage)[:draw] also gives a null pointer.
Using jl_exception_occurred() we have gathered that we get a KeyError (key not found) - so it seems PyCall is unable to find the given Python child-module - whereas the parent-module is found just fine.

We are running Julia 0.5 x64 on Windows - and PyCall is using Conda.jl.

Any ideas would be highly appreciated.