Hello,
My team has been problems with assigned sprints not showing in the activity history. Normally, when a task is created and assigned to a sprint, there is a history log saying "none -> Sprint x". However, this was not the case with this task. Even though my Sprint value on the right showed Sprint 15, there was no evidence of this in the history.
There was no history log of being assigned to Sprint 15 until I deleted Sprint 15 from the Sprint option, then reassigned it - as you can see in this screenshot

Has anyone else had this problem? Does it have to do with making the task using the create button in the board view instead of the "+create issue" option in the status's themselves? It is creating problems for us when we pull the changelogs via the Jira API.