When inserted into an InDesign document it appears to just import the image with its native resolution. (I've experimented with 72dpi and 300dpi)
It is possible to make it import the correct size if I take the generated file and make edits inside the file.
It's probably an error in the code library I'm using to generate the Word document, however since the document appears correctly in Word I'm asking for help here. If I could get some insight as to what is wrong with the file I can then file a bug report with the docx project. Alternatively if anyone knows how to just make it work I'd love to know.