Flashing Video on the UI, Output and Stream

Hello there,  I hope anyone can help with my issue.

Shots flash, showing the underlying layer.
Here's a video that better explain
https://www.deunido.com/WirecastShotsFlashing.mp4

We have a project with several shots made from the same cameras. (4 in total)

The shots are variations of the same cameras, with several PiP combinations, all over a Chroma background. The input device for the cameras is an AJA Io X3 (SDI)

We are running Wirecast 15.0.3 (We tried 15.1, but the system crashed, so we reverted) and Mac Studio with Monterey up to date.

The flashes start after a while when we are online, and deleting shots returns to normal.

Any ideas to find where is this coming from?
Has anyone with the same issue in the past?

Maybe the video backgrounds?

CUP is running at 40/60%, so it doesn't seem to be a resource issue.

I appreciate any help you can provide.