In the south of France, Navigator wanted us to take a motorway exit several times, only to lead us back onto the motorway immediately afterwards. We had already experienced this behaviour in Germany.
I've had this happen a few times over the last few years.
I think it can be related to traffic conditions when it tries to save a few seconds.
Are there limits on the time saved by taking an exit ? IMO a saving of a few minutes on a long journey is not worth the effort of taking a short diversion.