1490 changing Basecamp routes

Did this happen with routes you'd previously transferred without issue, or are these new routes?

If new then this could just be due to different routing algorithms between BaseCamp and your device, it's why having transferred a route and rebooted my devices I go back and compare again in BaseCamp.

As for shaping points, your 1490 cannot handle shaping or do not alert points so they will be converted to viapoints that do alert.

It would help though if you could post screenshots showing what is happening, perhaps the route in BaseCamp and the one on your device so we get a better idea of what you're seeing.

It will take me a while to get screen shots for this. On BaseCamp, I have loads for home use, Colorado Use, Florida Use...  Each with a collection of routes and waypoints.  

The shaping points for the routes that I have saved have never announced when I passed them.  When I've created a route, and sent it to the Nuvi, the route has copied they way it was designed on Base Camp.  Recently, it's started reshaping the route.  

For example, in North Dallas there is a tollway, Sam Rayburn tollway.  The highway is toll, the access roads are free.  So this sends me down the access roads.  10 miles on the access road, in North Dallas, at 4-5 pm, with a red light every quarter mile. Not the quickest route possible.   I reshape the route to another to dodge that section using way points and send it to the 1490.  The route snaps back to the slower route along the access roads.  Settings in BaseCamp and the Nuvi are set to avoid tollways.  

In the past, I've never had this issue.  I got the 1490 years ago when it was new and I've never had to redesign the route once it's on the GPS.  Everything was done on Basecamp and on Mapsource before.  

Now I have cleared my Nuvi and loaded my Florida load and looking at the map, the shaping points are flags, but I'm not driving from Texas to Southern Louisiana to test it.  LOL.  I've loaded my home load back on it and I've got a short trip tomorrow to Oklahoma and the route created on BaseCamp didn't need any shaping, and it seems to have been imported to the Nuvi without problems.  Tomorrow, we'll see.   

I did find an option in the settings that I am also experimenting with that might be the source of my problems though.  

Edit>Options>Device Transfer>Transferring Routes> Strip shaping points from routes on Transfer to device had been turned on somehow.  

And I got no idea why all this suddenly started up on a 13 year old GPS.  LOL

I'll let you know.. thanks.. 

I started having a lot of problems with my Nuvi 2699 after a somewhat newer update.
Check to see if there's been a subsequent update since the last one.

I've also replaced the micro chip (they do wear out over time).
Another possible problem, and I'm not sure it is a cause, is that there may be a limit to the number of waypoints one can download to the Nuvi.

Yes there is a limit, if by waypoints you mean Favourites? Points contained within routes don't count.

Points.  For example, if you wish, here is a route I'm planning to Baja California.  You can download it and import it into BaseCamp and it should work fine.  With this test route I was able to download it to my Nuvi okay.  ::  fazuri.com/stuff/Baja1test.gpx  fazuri.com/stuff/Baja1test.gpx

My Colorado load has the most waypoints in it.  I have 156 way points there.  But I only load that folder when I am heading to Colorado to go Jeeping.  Never had a problem with that load, but haven't been up there in a while.  These do not include the 5 or 6 Routing points that are listed in there.  

I haven't had any sort of major update on my 1490 in years.  I think that the last one was a update for a German Traffic Advisor.  

It's just that it does strange things, like if I am heading north, it directs me to drive 4 miles down a City Street, through 2 school zones to get on the Freeway that the other end of the freeway is a quarter mile from my house.  

Well that gpx file isn't a route, it's a track, so your 1490 wouldn't even be able to read it?

You may have gotten us mixed up?  My Nuvi is a Nuvi 2699 - probably newer than the 1490. 
To make that Baja file, I exported it from BaseCamp to the "GPS exchange format".  It's the same file that I downloaded into the Garmin - though I suspect that it does not download as a gpx file base on what you've posted.