The weird thing is I have 2 garmin devices the nuvi 2595 and the drive 50LM when I transfer the same trip to both devices the nuvi deletes items from the trips and the drive retains all points. so it has to definitely be with the device itself. I am an inspector and I use the trip feature every single day to figure out my route and it is a little annoying that I can't use the device I want (the nuvi) because of this issue. I would prefer to use the nuvi simply for the voice command feature. And if we are really being honest I would actually prefer to use my vehicle navigation, but Garmin didn't make it possible to transfer routes to it. I can't even upload saved points via USB which is annoying. If I could figure out an easier solution I would certainly use it!
Not sure why you feel Garmin should make it possible to update your vehicle navigation ... perhaps direct that at whoever makes your vehicle.
As for the issue with your nuvi, this thread is 7 years old, and refers to the older style of trip Planner, so unsure why you've resurrected it, but my nuvi doesn't delete items from the trip. Could you please start a new thread with a more detailed explanation of your problem. Thanks