Tried to load up the Rivet IOW Class 484 into formation designer, but it crashed the game twice (I tried twice) & had to force shut the game through a PC restart as the game wouldn't allow me in Task Manager! (right click, close on task bar done nothing either)
Try again guys. I managed to get this 6-car set running in-game OK. Mind you I did then get a crash when I went back in and tried to tweak the formation. (I have inner and outer 2-car units where the inner ones don't have the red cab and I put one set in the wrong place and wanted to change it). So I think you can 'create' and 'delete' but not 'replace' with the CL484.
And now, some 24 hours later, my CL484 formation doesn't show up in FD. So no idea what is going on now? (And like you I then have to Ctrl-Alt-Delete to get out of FD).
And now it is back again !!! This has been an 'interesting' journey. At first everything worked OK and I just thought I was lucky. Then everything vanished and Formation Designer just locked up with the CL484. (Even to the point that deleting the formation and starting again didn't work). Then I renamed to formation (no spaces or underscores) and everything seemed to work again. So now I'm leaving well alone.
I've only just realised that somehow, with the messing about in FD, I have 'lost' my headlights. Although you can see the 'glare' on the platform in the above screenshot the lights aren't lit. Compare that with the earlier screenshot two posts above and you can see the lights used to be lit correctly. (Ditto the screenshot below which I have just taken today........although, in this case, the lights might have been knocked out by hitting the bridge).