When your Cucumber feature seems to forget cookies / sessions when you run it with Selenium check if the test travels in time like here:

Given the date is 2017-10-20
When I sign in
Then I should see "Welcome!"

Rails Long Term Support

Rails LTS provides security patches for old versions of Ruby on Rails (2.3, 3.2, 4.2 and 5.2)

• Prevents you from data breaches and liability risks
• Upgrade at your own pace
• Works with modern Rubies

Read more Show archive.org snapshot

What happens here is that the Rails application serving pages runs in 2017, but the process running your browser still lives today. This huge gap in time will expire most cookies immediately.

If all you need is to freeze the time to a date, a workaround is to travel to the future instead.