After archiving app in Xcode, how to be able to use source control again?

I archived my application in Xcode (using 8.3.3) to submit to the App Store.

I made some changes to the source today and went to commit the changes, but it is showing up as no version editor, and the "Commit Files" button is disabled.

After running the app on simulator I tried to use source control again, and this time the Commit Files button was enabled, but after I clicked it, it said "No Version Editor" in the main pane there.

Is there something I must do to reactivate source control?

I need to continue to work on the project.