I just updated Basecamp to 4.2.1 and maps to CNNA 2014.10. I have 2014.10 selected in both BC and the Montana 600. The Montana has also been updated to 5.1 firmware.
I created a simple new route on BC and sent it to the Montana. Now when I try to use this route I get a message on the Montana that "This route does not match the available maps and will not follow the roads precisely. Do you want to recalculate the route?". I've checked that maps are the same on both sides. I've checked and it seems that routes already existing on the Montana do not generate this message using 2014.10 or 2013.4, only new routes created in BC 4.2.1.
Any ideas?