I had the same issue but with the cipher collectible. I completed the Crimson Wastes activity card and the trophy didn't pop. Went to in game settings - enabled the option to start online. Quit the app, relaunched and the trophy popped when I started the first biome. I can't guarantee that it will work for you the same way though. 😬 After 100+ runs on the first biome I can confirm that it is total RNG. The room with the scout log spawned finally so keep on trying Room looked exactly like the one shown in a tweet few posts above.