i will lower the platform, you can try to access it with a rocket jump.
Try holding out the jump button as well. Very sorry for the inconsistency.
This room has always had a weird inconsistent entrance here, I think your machine might be a bit lower end than mine and the time is not computing quite right, totally my bad.
You can also try to up your framerate by cutting something in the background, I'm sorry I will fix it in the next build, and if nothing works you can use the debug console just for this one.