Text doesn't display at the right moment

Hello,

I am using xibo 1.6.0. I am testing my client when it lose connection to the server. So i put the layout I want as "Default layout" and after, I disconnect my server.

I am trying to diplay a scrolling text during a video and I want the text to start at 30 seconds.
So i put a transparent png that last 30 seconds before my Text (in the Region time line).
But the text doesn't start at the right moment. It starts later and later every time the layout restart.

I really don't understand why... Is the default layout really downloaded on the client if we make minor modifications on this layout ?

Thank you