Didn't answer here because we did talk over email, but I do now for other people to know and share a little trick meanwhile this is fixed.
It actually is something wrong (support dixit
) with some Logitec cameras' highest resolutions and Modul8 v3 (also v3.1 which I'm using now), so while they are fixing it, I am using a megasupersimple Quartz Composer composition to have the FullHD of Logitech C922 camera running on Modul8 (.qtz file attached).
It is only a video-input node to a billboard (and a clear). The video-input source is set to default so there shouldn't be necessary to edit it to run with any camera, whenever it's the only one running on the computer.
Just use the composition in Modul8 as a regular video.
Be aware that not only the stage dimensions should be FullHD on "Project Settings" but also the Quartz Composer dimensions below in the same window.