Not adding, deleting or adding products to cart?

Hello craigsbarber, when you deactivated WP Super Cache and WP Optimise, did your wishlist started to work?

Ok, I have worked it all out now, everything works perfect, adding and removing.

Filename = class.yith-wcwl-init.php
Change;
var yith_wcwl_plugin_ajax_web_url = '<?php echo admin_url('admin-ajax.php') ?>';

TO

var yith_wcwl_plugin_ajax_web_url = '<?php echo admin_url('admin-ajax.php', (is_ssl() ? 'https' : 'http')) ?>';

Filename = class.yith-wcwl-init.php
Change;
var login_redirect_url = '<?php echo wp_login_url() . '?redirect_to=' . urlencode( $_SERVER['REQUEST_URI']) ?>';

TO

var login_redirect_url = '<?php echo wp_login_url() . '?redirect_to=', (is_ssl() ? 'https' : 'http') . urlencode( $_SERVER['REQUEST_URI']) ?>';

Filename = class.yith-wcwl-init.php
Change;
'<a href="' . admin_url( 'admin.php?page=' . $wc_settings_page . '&tab=yith_wcwl' ) . '">' . __( 'Settings', 'yit' ) . '</a>',

TO

'<a href="'http') . $wc_settings_page . '&tab=yith_wcwl' ) . '">' . __( 'Settings', 'yit' ) . '</a>',

Filename = class.yith-wcwl-ui.php
Change;
$html .= '<img src="' . esc_url( admin_url( 'images/wpspin_light.gif' ) ) . '" class="ajax-loading" id="add-items-ajax-loading" alt="" width="16" height="16" style="visibility:hidden" />';

TO

$html .= '<img src="' . esc_url( admin_url( 'images/wpspin_light.gif', (is_ssl() ? 'https' : 'http') ) ) . '" class="ajax-loading" id="add-items-ajax-loading" alt="" width="16" height="16" style="visibility:hidden" />';

Filename = class.yith-wcwl.php
Change;
return admin_url( 'admin-ajax.php?wishlist_item_id=' . $item_id);

TO

return admin_url( 'admin-ajax.php?wishlist_item_id=' . $item_id, (is_ssl() ? 'https' : 'http'));

The plugin now works PERFECTLY for me now, I am no longer having issues with it working, on FORCE ADMIN SSL or otherwise.
For someone who knows nothing about PHP, I have done what the makers of the plugin could not do it seems.

I have tested this on two different themes that were not working previously – both now work.

If you have a cache plugin such as WP Super Cache, make sure you clear the cache (I removed mine totally from wp-config and disabled the plugin).

It is scary that the people who made this plugin also make e-commerce themes and are not using SSL or even testing their plugins with SSL active.

Thank you damiafaw for your wonderful work! I tried it, though, and it didn’t solve my problem, but I am sure it is fine left in place. What did help was going into WP Super Cache>Advanced and adding “wish-list/” (do not include quote marks; this is the url extension to my Wish List page, so use whatever yours is) into the “Add here strings (not a filename) that forces a page not to be cached”, on its own line after wp-.*\.php and index\.php that were already there.

And finding that was a total piece of good luck after fiddling with the problem for half a day, and getting nearly lost in the problem solving process! Almost went to WooCommerce Wish List which has improved over the time I tried it about 6 months ago; still considering that solution.