Yes, sorry, and I was slightly unclear, as well. I am also referring to the test cycle getting lost - due to how my dev team uses Jira we don't have releases set up in the way that Zephyr uses to create release folders, so I'll set up test cycles in the Unreleased > Unscheduled folder by default.
When I had too many (15? 20?) test cycles in Unscheduled they started not appearing in the left hand navigation tree, but I could Search Test Executions where I could see, and navigate to, the test cycle so I knew they weren't actually missing. I created a fake release named "2021" for the Jira project, the folder showed up in the Cycle Summary tree under Unreleased, I moved last year's test cycles into it, and the "missing" test cycle popped back up in the Unscheduled folder.