Hello,

The breadcrumbs do not have space enough on mobile that is why they are hidden.

I can give you custom CSS, however, breadcrumbs would not look good on mobile.

You can try this code:

@media (max-width: 991px){
body .single-breadcrumbs-wrapper .woocommerce-breadcrumb, 
body .single-breadcrumbs-wrapper .yoast-breadcrumb {
    display: inline-block;
}
}

Please insert the code into the Theme Settigns > Custom CSS > General.

Best Regards