Lost layout after creating new page with no template chosen

Hello,

I modified the fixer theme home page.
Then I added some WPMUDEV plugins.
Then I added a new Page from WP-Admin and did not select a template.
I saw the warning at the top but I believe it does not apply.

Now the homepage appears to have lost it's layout.

Any ideas on getting the layout back and how I can avoid this in the future?

Thanks!