Loosing Feedback master artwork

I have the same drag and drop in two different story files. I'm doing some experiments to see what I can learn.

In one, when I set the drag and drop to show Thank you feedback at the end of the interaction.

The strange part is somehow I am loosing the Thank you layout master in one of my files. And I had this happen with some other tests I was running. Usually what seems to happen is the background for the dialog box is lost and the text and button just appear over the top of the slide.

So the questions are:

What am I doing that could cause this? And how to avoid it in the future?  I know that I didn't go into the Feedback masters and delete the layout. I may have turned the feedback on/off, deleted or modified the layer, and/or changed what type it is.

How to fix it? Regardless of how it happened, it has happened and I need to fix it. I noticed there is a question feedback master panel when I select the inserted layer. But that only seems to allow me to choose the master, not the specific layout I want.

I also copied the thank you layout from the one that was working and pasted it into the one that wasn't. That worked (although the layout changed its name from Thank you to Custom. And in this case it worked because they were both built on the same design and in any event are just some tests. So what do I do if I'm actually in the middle of a project and I loose a feedback layout?