Random recalculations using routes shared from older units

Just returned from a trip to the Pyrenees with a small group. Our routes were pre planned on Mapsource using older maps ( the Nav VI releases new maps earlier than Zumos). The Zumo 660 worked perfectly with this technique. I only upgraded to a Nav 6 after the 660 fell out the mount on my other bike and bounced down the road. I was warned that the Nav 6 doesn't like Mapsource and that if you want to follow the chosen roads, you need to open gpx routes using Basecamp and add shaping points to them. I did that but the Nav VI still recalculated them when they were selected each morning and changed the routes. It then recalculated them as we went, even recalculating for no apparent reason when it was actually on route; sometimes coming up with the original route again and other times creating a new one. It still recalculated the route with auto recalculate turned off and when set to prompted recalculate calculated anyway despite selecting NO. It decided for itself and recalculate regardless. Totally weird. Fortunately I could just follow my pals, trying to understand what was going on.

Still bemused when I got back, I contacted BMW customer service for assistance. Nathaniel replied, "I’m not technically trained in this field so I can’t answer the queries you’ve asked - The best thing to do is to go to your local Centre and a technician will be able to help." If there is a Basecamp/Navigator expert at my dealer who might have the answer, I've not met them, which is why I asked BMW in the first place: routing me back there is about as helpful as the Nav VI routing itself. Seems like BMW have the expertise to create this stuff, or at least get Garmin to do it for them, but lack the wit to train their people in its use.

Can anyone explain what's going on to cause this, and how to prevent it? For sure, someone will have the same issues and have solved them; I will keep trawling the web for a solution. And, if I discover it, I will post it on here.

There is quite a lot to digest in that post but let's try to start with the recalculation whilst on a route, even when recalculation is set to OFF or Prompted only, when the reply to the prompt is NO. Diagnosis from a distance, as the Nutty's Law thread shows, is often difficult but here goes:

I wonder if you have your preferences set correctly? From straight out of the box, my Nav VI had certain routing preferences set as ON (ticked). From memory these were to avoid lane sharing, avoid seasonal closures and a couple of others. It's possible, I guess, that these instructions 'Not to do something' (ie don't take me up a pass or road that has seasonal closures) might trump the command not to recalculate? Is that possibly what happened to you?

Recalculation of routes that were created in different mapsets, often by other bods and in accordance with assorted different settings, will often take place on import into a device; that is nothing new nor particular to the Nav VI. It's learning how and why it can happen that's the key. There are lots of threads on the subject but you'll have to patiently sieve out the twaddle from some.

There is no really good reason why a route cannot be created in BaseCamp or Mapsource for import into a Nav VI or any other Garmin 'Road' centric device. It's why .gbd (Garmin's own) and / or .gpx (the industry's generic exchange format) file extensions were developed. Most of the mistakes using Garmin computer based software are now down to user error. Start and end in Garmin software and the chances of big errors are definitely reduced.

Where glitches do most often occur is where a route is created in third party software, where the maps used are different, creating other problems. These too are sometimes down to simple user error as well. Helping bods with these is more difficult as the use of third party software has brought in yet another possible variable, over and above whatever else the fellow may or may not have done. If there is one golden rule: Keep it simple.

Thanks for your thoughts on this. I think there may well be an element of operator error or mis-setting of options in the satnav but I can't see where; which is why I asked BMW for their help. I unchecked all the avoidances when I got the unit - seasonal closures particular generally mess up mountain routes. The shared routes were created on Mapsource using an older set of maps than mine but I imported them into Basecamp and re-plotted new versions with shaping points routes. I have the same maps on the unit & my PC but it seems to recalculate on opening the route in the trip app regardless. On factory settings the Nav VI won't import from Mapsource although you can use a hidden menu to change that. I'm still not sure what lays behind it and "sieving" forums looking for answers. For sure, they are more help than BMW can offer right now. I stayed with Mapsource when Basecamp came out, largely because I was familiar with it & it did what I wanted. With the Nav VI, I am discovering Basecamp thanks to some very helpful guys on YouTube. I note that you can select to transfer routes with or without shaping points - I plan to upload routes in both formats for my next trip and see what difference that results in.