When selecting the "update" button in the "edit" screen, the selected component is reset. After that, the link between the bug and the component is lost. The version field does not have the same problem. Setting the component again later works fine, but once it is set, next time you edit the bug, it disappears again.

I found this issue using a customized workflow, where a status transition shows the "edit" screen. I am able to reproduce it to using the "edit" operation on a brand new default installation, so I think the bug is appearing wherever the "edit" action is referenced.
However, I have defined projects where this does not occur, I was not able to find the reason why.

Steps to reproduce:

• start a brand new default installation of Jira 3.7.3, with an empty database
• create a default project names "Test" with key "TST" and project lead "root", all other settings are default
• create a component named "C1"
• enter a new issue, and select component "C1" to log the issue against
• select the "edit the issue" operation
• update the issue without changing anything
• the component will be reset to nothing