To replicate:

1. Edit the value in the Environment field for an issue.
2. Remove the Environment field from the "View" screen.
3. View the issue again.

The issue summary screen shows the Environment field box, without any contents. When you add the field back onto the screen, the Environment field shows with the contents.

I didn't test this thoroughly so let me know if it doesn't replicate on your side. I also did some funny things with the renderers before this bug occurred.