In a project I go to "Tests", enter the name of a test cycle and get a list.
When clicking on the Arrow-symbol of an item of the list, the (existing) tests don't open. It seems to happen when the tests are not new, but a few months old.
I tried Zephyr re-indexing, Cycle cleanup and cleaning up the cycle cache - nothing helped.
JIRA: 8.6.1
Zephyr: 5.4.1.54108287
