no, they are not assigned to the footer nor are they overlapped
In this case, do the following:
Then we will have a closer look.
It looks like you have checked this?:
no, that's not the problem
Muse is no human and can’t know, which of your responsive elements should influence (push down, lift up) which other element.
On you page, the lower image could be affected by the logo (upper left), the menu bar or the upper image.
Help Muse to understand, what you want to achieve: Group the two images, and all works fine!
For deeper explanations, see this short video, which deals with a similar issue: https://forums.adobe.com/docs/DOC-9082
Alright, thank you very much