It's also possible that aircraft aren't following the exact track you see on RadarBox24.
It all depends how many intermediate points are processed on their network (to save bandwidth). Tracks are constructed by "joining the dots", which doesn't really matter on a straight airway, as you can't tell how many points have been used, but where a change of heading occurs missing points may appear to show the flight cutting the corner even where has flown directly overhead the fix.