Some of our demos, which were built with our Theme Builder, may have Elementor headers and footers that sometimes go missing after importing the demo.
So to activate the header, please go to WP Dashboard > Avas > Theme Builder > Header > Manage Conditions > Add Conditions > Entire Site > Save Conditions.
Do the same process for the footer as well.
N.B.: If you couldn't find any header or footer on the Theme Builder, then please share your website login details so we can check it for you.
After clicking the Manage Conditions button, you will see a pop-up like below