cap development whenever:update_crontab silently succeeds, does nothing

When I run cap development whenever:update_crontab, it appears to silently succeed, with no output, and the crontab on the server is not updated. Likewise, cap development deploy shows no whenever-related activity.

In my Capfile:

require 'whenever/capistrano'

In deploy/development.rb:

In my deploy.rb:

set :whenever_identifier, -> { "#{fetch(:application)}_#{fetch(:stage)}" }
set :whenever_environment, -> { fetch(:stage, 'production') }

My schedule.rb:

set :output, 'logs/dash2-harvester.log'

every 15.minutes do
  command "STASH_ENV=#{@environment} /apps/dash2/apps/dash2-harvester/bin/harvest.sh"
end

Reproduce cap development whenever:update_crontab and cap development deploy, then inspect Capfile, deploy/development.rb, deploy.rb, and schedule.rb alongside the required Whenever integration. Done means the update command reports activity and the server crontab reflects the scheduled harvest command, with deployment showing the related activity.