Remove shipping method display on front_end option, it is not working and it's not straight forward to make it work correctly

app/views/spree/admin/shipping_methods/_form.html.haml

@@ -18,7 +18,7 @@
       .alpha.three.columns
         = f.label :display_on, t(:display)
       .omega.eight.columns
-        = select(:shipping_method, :display_on, Spree::ShippingMethod::DISPLAY.collect { |display| [t(".#{display}"), display == :both ? nil : display.to_s] }, {}, {class: 'select2 fullwidth'})
+        = select(:shipping_method, :display_on, [[t(".both"), nil], [t(".back_end"), "back_end"]], {}, {class: 'select2 fullwidth'})
         = error_message_on :shipping_method, :display_on
 
   .row

config/locales/en.yml

@@ -3221,9 +3221,8 @@ See the %{link} to find out more about %{sitename}'s features and to start using
           zone: "Zone"
           calculator: "Calculator"
           display: "Display"
-          both: "Both"
-          front_end: "Front End"
-          back_end: "Back End"
+          both: "Both Checkout and Back office"
+          back_end: "Back office only"
           no_shipping_methods_found: "No shipping methods found"
         new:
           new_shipping_method: "New Shipping Method"
@@ -3235,9 +3234,8 @@ See the %{link} to find out more about %{sitename}'s features and to start using
         form:
           categories: "Categories"
           zones: "Zones"
-          both: "Both"
-          front_end: "Front End"
-          back_end: "Back End"
+          both: "Both Checkout and Back office"
+          back_end: "Back office only"
       payment_methods:
         new:
           new_payment_method: "New Payment Method"

db/migrate/20200508101630_convert_frontend_shipping_method_to_both.rb

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+class ConvertFrontendShippingMethodToBoth < ActiveRecord::Migration
+  def up
+    # The display_on value front_end is not working
+    #   (it's not being used in the back office to ignore shipping methods marked as front_end)
+    # So, here we are converting all entries to the more generic "both" option
+    #   both is represented as nil in the database
+    # # This enables us to remove the front_end option from the code
+    execute("UPDATE spree_shipping_methods SET display_on = null WHERE display_on = 'front_end'")
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20200430105459) do
+ActiveRecord::Schema.define(:version => 20200508101630) do
 
   create_table "adjustment_metadata", :force => true do |t|
     t.integer "adjustment_id"