297 120 ft Roundhouse Left End,<kuid:522774:100054>
I just deleted it from CM 3.5 and downloaded it again, comes up clean here. Make sure you're not confusing it with the original;
120 ft Roundhouse Left End,<kuid:90361:1504>
That one is missing a texture file, which makes the interior show up white in TS2010 and not work at all in TS12. Phil Skene and I were apparently thinking along the same lines at the same time, he uploaded his own set you could try;
120 ft Roundhouse Left End TS12,<kuid2:69871:2083:1>
120 ft Roundhouse TS12,<kuid2:69871:2081:1>
120 ft Roundhouse Bay with Entrance TS12,<kuid2:69871:2082:1>
120 ft Roundhouse Right End TS12,<kuid2:69871:2084:1>
Another thought, have you looked at this?
http://forums.auran.com/trainz/showthread.php?t=54116
That probably also applies to TS12,
" In the CMP the dependent sign is red with missing assests,"
The only dependency it has is;
inviso rail,<kuid2:67598:38001:4>
Which is built into TS12. Possibly you opened that for edit somehow, try clicking on inviso rail and select Edit, Revert to Original.