Redis – After upgrading Sidekiq to v6, it doesn't automatically start in production

Here’s an output from Capistrano:

02:05 sidekiq:start
      01 sudo service sidekiq start index=1
      01 sidekiq (1) start/running, process 26392
    ✔ 01 deployer@IP 0.721s
      02 sudo service sidekiq start index=2
      02 sidekiq (2) start/running, process 26505
    ✔ 02 deployer@IP 0.728s

After logging to the server and ps aux | grep sidekiq, there’s no process running. So I go back to my local terminal tab and run

cap staging sidekiq:start

and the new Sidekiq process shows up for a few seconds on the server:

ps aux | grep sidekiq
deployer   489 52.0  1.0  76344 40856 ?        Rs   13:13   0:00 /home/deployer/.rvm/rubies/ruby-2.6.3/bin/ruby /home/deployer/.rvm/gems/ruby-2.6.3/bin/bundle exec sidekiq -i 1 -e staging
deployer   695  0.0  0.0  10472   936 pts/0    S+   13:13   0:00 grep --color=auto sidekiq
deployer 32744 42.2  1.4 111100 56188 ?        Rs   13:13   0:02 /home/deployer/apps/app-staging/shared/bundle/ruby/2.6.0/bin/sidekiq -i 2 -e staging

But after a few seconds, it will disappear.

If I run from the server RAILS_ENV=staging bundle exec sidekiq – Sidekiq is running. But the second I restart the server/deploy new code, the Sidekiq process gets killed.

Here are my rake tasks for Sidekiq:

namespace :sidekiq do
  desc "Tells Sidekiq (with signal TSTP) it will be shutting down at some point in the near future."
  " It will stop accepting new work but continue working on current messages"
  task :quiet do
    on roles(:app) do
      puts capture("pgrep -f 'sidekiq' | xargs kill -TSTP")
    end
  end

  desc "Signals that Sidekiq should shut down within the -t timeout option given at start-up (see config/sidekiq.yml)."
  " It will stop accepting new work, but continue working on current messages (as with USR1)."
  " Any workers that do not finish within the timeout are forcefully terminated"
  " and their messages are pushed back to Redis to be executed again when Sidekiq starts up. "
  task :terminate_gracefully do
    on roles(:app) do
      puts capture("pgrep -f 'sidekiq' | xargs kill -TERM")
    end
  end


  desc "Starts sidekiq workers. Fails if there are already running processes."
  task :start do
    on roles(:app) do
      pids =  capture("pgrep -f 'sidekiq'; true")
      puts "Present sidekiq process pids #{pids}"
      if pids.split("n").count == 1
        # For each worker service with index ID is called
        execute "sudo service sidekiq start index=1"
        execute "sudo service sidekiq start index=2"
      else
        puts "##------------------------------------------------------------------##"
        puts "Sidekiq was not terminated before start execution. Wait untils it is finished and start it again (or kill the processes)."
        puts "##------------------------------------------------------------------##"
      end
    end
  end

  task :restart do
    invoke "sidekiq:terminate_gracefully"
    invoke "sidekiq:start"
  end
end

Why is Sidekiq v6 not being automatically started by Capistrano?