IME there are often preview problems with YouTube vids when the url parameters include lists, or channels, or sharing IDs or other mumbo jumbo. They’re sure to work if the url only has the basic video ID like:
https://www.youtube.com/watch?v=EK_V0t0KmiQ or equivalently https://www.youtu.be/EK_V0t0KmiQ
and optionally a start time.
So all I did was trim out everything except the video ID and the start time you included. Often that other mumbo jumbo is only valid in the context of your login. So it’ll look fine to you, but anybody else gets an unavailable message and clicking through just drops them at the YouTube homepage with no idea what content they’re supposed to be seeing.