I seem to be having the same troubles again when updating hardware. I got a new tiu for my G scale RR outback. I use the system in the basement during the winter. I had an old TIU that I swapped out and now when I build a consist, the next day I have troubles.
I built a consist of 2 engines. It worked fine. The next time I went to run it, it said lashup address #60 not found. I can call up that engine and it will run. I pressed read to assign the engines to the new TIU thinking that maybe the problem? No luck as it still says it can't find the lead engine. Again I call it up, it starts fine and operates normally. I went back to using DCS V4.2. Is there some other issue??
I'll rebuild the consists that I need to, but last time I got new hardware, I ended up having to re-add every engine and consist. I'm doing something wrong. Do the read button pushes only associate the engine to the new TIU temporarily? Seems like a new session causes the issues to pop up.