So, the reason was really stupid. Just the settings in my Chrome browser. Although, no idea why it’s different with Julia’s installation of Jupyter than on the Anaconda’s.
On the other hand, now I don’t seem to get it to work… The kernel keeps dying 
EDIT: In case anyone reads this in the future, you have to start the notebook from the Julia environment with the dir keyword:
using IJulia
notebook(dir="path/to/environment")