Hi Captain John,
I'm happy to hear that it was a simple fix. There are so many computers in modern trains that they can sometimes get confused, and a hard re-boot often helps.
As far as running multiple Legacy loco's on one track goes. No, I've not encountered any problems with that. I normally have up to 6 running at once. My layout is basically a double tracked loop, but it is normally wired as one electrical block, and so is effectively a single track.