Hi @chesty - let’s see what we got here  please do the following:
 please do the following:
1.) Create a file called debug_issue.rb in your Zammad directory (usually /opt/zammad)
2.) Run the file from your Zammad directory via zammad run rails r debug_issue.rb or rails r debug_issue.rb as zammad user, depending on your installation source (package/source)
3.) Post the output here. Make sure all sensitive data is anonymized! If you want you can drop it as an email to support@zammad.com. Please refer to this thread and me 
4.) Delete the debug_issue.rb file
require 'mixin/rails_logger'
module Mixin
  module RailsLogger
    def self.logger
      @logger ||= Logger.new(log_to).tap do |logger|
        logger.level = :debug
      end
    end
    def self.log_to
      # STDOUT
      'debug_issue.log'
    end
  end
end
ImportJob.create(name: 'Import::Ldap').start