You receive incorrect turn instructions, maybe even in the opposite direction? This issue is usually created when importing GPX files. The coordinates in the GPX files might be slightly different to the coordinates mapped in OpenStreetMap. Due to that it can happen that a point placed close to an intersection leads to a very short turn off the road and back. If you watch out for some pitfalls during the GPX import, everything should work as expected, see our tutorial on importing GPX files.
If you did not import a GPX track, but received incorrect turn instructions, the reason could be that you placed a waypoint on an intersection, which can in some cases create incorrect turn instructions. We highly recommend to place waypoints on roads and not intersections, this can lead to unexpected routing results (we update our road data every week, small changes of the data can move your waypoint to the wrong side of the intersection). Other reasons could be incorrect OpenStreetMap data or maybe a bug in our turn instruction generation. Please feel free to contact us so we can further support you or fix the issue.