1. Called Proxy Policies Chain Update API
2. The policy chain is updated, but "Promote v. x to Staging APIcast" is active.
3. The button cannot execute. Just keeps active.
4. After modified some configuration of the product, like changing error messages or change policies chain, they can promote the configuration to staging and "Promote v. x to Staging APIcast" to "Nothing to Promote".

The reason for this is that this method returns true even though it should return false.

  def pending_affecting_changes?
    return unless apicast_configuration_driven?
    config = proxy_configs.sandbox.newest_first.first
    return false unless config
    config.created_at < affecting_change_history.updated_at
  end

And when the database is PostgreSQL, this can occur frequently because timestamps are recorded in microseconds. In contrast, MySQL records timestamps in seconds, so this issue is unlikely to occur.