Hi,
Thank you for the details.
I see a few conflicting custom CSS rules in the site header. One is hiding the search input under a certain resolution. The container position is also set behind the menu bar. Try this custom CSS to resolve these.
.plsh-search {
position: relative;
min-width: 280px !important;
}
.plsh-search .asp_m input.orig {
display: inline;
}
Use the min-width attribute to change the minimum width of the search bar, to which it cannot get below. Please also note that these rules might not work in all cases though.