Found my fix: Also had to change this:
Change yes to on.

wp-content/plugins/woocommerce-tab-manager/woocommerce-tab-manager.php
From:
if ( ‘yes’ == $override_tab_layout ) {
// product defines its own tab layout?
$this->product_tabs[ $product_id ] = get_post_meta( $product_id, ‘_product_tabs’, true );
To:
if ( ‘on’ == $override_tab_layout ) {
// product defines its own tab layout?
$this->product_tabs[ $product_id ] = get_post_meta( $product_id, ‘_product_tabs’, true );

Also:
/wp-content/plugins/woocommerce-tab-manager/admin/woocommerce-tab-manager-admin-functions.php and look for this line 102:
<label for=”_override_tab_layout”><?php _e( ‘Override default tab layout:’, WC_Tab_Manager::TEXT_DOMAIN ); ?></label> <input type=”checkbox” name=”_override_tab_layout” id=”_override_tab_layout” <?php checked( $override_tab_layout, “yes” ); ?> />

Replace it with:
<label for=”_override_tab_layout”><?php _e( ‘Override default tab layout:’, WC_Tab_Manager::TEXT_DOMAIN ); ?></label> <input type=”checkbox” name=”_override_tab_layout” id=”_override_tab_layout” <?php checked( $override_tab_layout, “on” ); ?> />