Look at this design view screenshot, where the two snippet objects "test1" and "test2" are placed one on the page and the other inside a TabTop MultiLayoutRegion:
This is the code of the two snippets:
You can see that they are displayed correctly in the design view.
However, when published in the browser, the CSS for the "test2" snippet is missing:
If you look at the source code in the browser, you can see that the CSS code for the "test1" snippet is there in the head section:
But the CSS for the "test2" snippet is missing in the source code!
So it seems that NOF "forgets" to create the CSS statement for the header when the snippet is inside a MultiLayoutRegion?