It sounds like you opened the Content aware workspace.
The green area allows you to choose from where the content aware fill will take content, and by erasing the green where it will ignore content.
You can then go on to click OK, Apply or Cancel. The latter takes you back to the Photoshop workspace without any fill.
This is not a bug, just a feature of which you were not aware - I've moved your post from bugs to discussions.
https://helpx.adobe.com/uk/photoshop/using/content-aware-fill.html
Dave