There is no restriction against left turns here.  OSM data produces the expected results with GraphHopper, OSRM and Valhalla, see https://www.openstreetmap.org/directions?engine=graphhopper_car&route=50.86157%2C4.42061%3B50.86232%2C4.41744

It looks like the problem is not with OSM data but with Magic Earth.  You may want to report this to the devs.