Ok, so actually combination of both suggestions did the trick for me:
- adding 1.8.4 to PATH manually (since I got it through juliaup)
- running the terminal as admin
Separately, they did not work.
Is there any risk of having only one version in the path?
(also just as a precaution for others - the Julia webpage is not super explicit as to what is the actual path, so first I have inserted the address without \bin at the end which led to couple of my other programs crash when executing the precompile command 
).
If there would be need to do some more testing, I am up for it.