Normally, I would suggest to ask the developers directly. Unfortunately, NC has no own client developers yet. So you can only report this to the owncloud-client team. Therefore it would be better to reproduce this problem on a complete owncloud setup because for NC issues they don’t know if this problem is related to NC.
@nickvergessen, @jospoortvliet can you help this user somehow, can the client-theming-repo be used for this purpose?