Video player on IPad with Sidecar in cubase 11


I just bought a IPad Pro 12,9" to have my video player on it using apple sidecar!

Unfortunately, when I first launched it, it was laggy and unusable. I try to use a wire connection between my Mac and my iPad but the video won’t show anymore.
Now, when I slide my video player to my iPad, the video freeze and becomes inactive. After many try without changing anything, it work but right after putting it in full screen, the issues start again…

I’m thinking about to use a MTC video software to workaround but I won’t buy one before understanding the problem with the video player of cubase !

Is that a common issue with a second screen monitor or does it come because of this setup ?

(I’m working on MacOS BigSur)

Thank for your help!