Custom Platforms do not get initialized unless the player restarts the map through the pause menu on the following platforms:
The First;
Origins;
Triangle;
Nice;
Big Mirror;
Dragons;
Monstercat;
Crab Rave;
Panic;
Green Day;
Timbaland;
Fit Beat;
Kaleidoscope;
Skrillex;
And for V3 Environments it initializes properly except no existing objects are removed so the Custom Platform is just added on top of the environment.
Here's a video of me testing with a platform that can be found on model saber and it's link as well as the log file for the testing:
https://modelsaber.com/Platforms/?id=1618413935&pc
https://streamable.com/n7oq9f
_latest.log