Rails route disambiguation - ruby-on-rails

Question

Rails version: 5.2.3
Ruby version:2.0.4
In the below I am using concerns with post to overcome size limitations imposed on gets. It ends up clashing with #show and I can't figure out how to disambiguate them.
routes.rb
require 'sidekiq/web'
Rails.application.routes.draw do
concern :with_datatable do
post 'datatable', on: :collection
end
resources :organizations, concerns: [:with_datatable]
mount Sidekiq::Web, at: "/ninjas"
end
my routes are as follows:
datatable_organizations POST /organizations/datatable(.:format) organizations#datatable
organizations GET /organizations(.:format) organizations#index
POST /organizations(.:format) organizations#create
new_organization GET /organizations/new(.:format) organizations#new
edit_organization GET /organizations/:id/edit(.:format) organizations#edit {:id=>/[0-9]+/}
organization GET /organizations/:id(.:format) organizations#show {:id=>/[0-9]+/}
PATCH /organizations/:id(.:format) organizations#update {:id=>/[0-9]+/}
PUT /organizations/:id(.:format) organizations#update {:id=>/[0-9]+/}
DELETE /organizations/:id(.:format) organizations#destroy {:id=>/[0-9]+/}
sidekiq_web /ninjas Sidekiq::Web
rails_service_blob GET /rails/active_storage/blobs/:signed_id/*filename(.:format) active_storage/blobs#show
rails_blob_representation GET /rails/active_storage/representations/:signed_blob_id/:variation_key/*filename(.:format) active_storage/representations#show
rails_disk_service GET /rails/active_storage/disk/:encoded_key/*filename(.:format) active_storage/disk#show
update_rails_disk_service PUT /rails/active_storage/disk/:encoded_token(.:format) active_storage/disk#update
rails_direct_uploads POST /rails/active_storage/direct_uploads(.:format) active_storage/direct_uploads#create
Navigating to the route, /organizations/datatable.json produces this error:
OrganizationsController#show is missing a template for this request format and variant.
It thinks /organizations/datatable.json is a match for /organizations/:id/show despite having a clear route for /organizations/datatable(.:format)
Here's my controller:
class OrganizationsController < ApplicationController
def index
#title = "Organizations"
#page_description = "Organization data warehouse"
#page_icon = "institution"
#organization = Organization.new
#load = {data_table: true}
respond_to do |format|
format.html
format.json { render json: OrganizationDatatable.new(params) }
end
end
def datatable
respond_to do |format|
format.json { render json: OrganizationDatatable.new(params) }
end
end
def get_raw_records
Organization.all
end
def create
end
def edit
end
def destroy
end
def show
end
def update
end
def new
end
end
full error text:
ActionController::UnknownFormat - OrganizationsController#show is missing a template for this request format and variant.
request.formats: ["text/html"]
request.variant: []
NOTE! For XHR/Ajax or API requests, this action would normally respond with 204 No Content: an empty white screen. Since you're loading it in a web browser, we assume that you expected to actually render a template, not nothing, so we're showing an error to be extra-clear. If you expect 204 No Content, carry on. That's what you'll get from an XHR or API request. Give it a shot.
What am I missing here?