Sometimes time tracker window shows wrong artifact – not the one I'm working on (timesheet has the current artifact right). It starts to show invalid issue when the user gets an error (upload error for example).
Reproduction sequence (JIRA Client):
1. Select issue A, start work on it.
2. Edit issue B: remove summary, Save&Upload.
3. Wait until error notification is shown ("Cannot upload illegal values")
4. Observe: time tracker window shows issue B.
Restarting time tracker window fixes the problem.