Illustrator loses focus after editing in group
When a group is double clicked to edit inside (isolation mode), on leaving isolation mode the Illustrator application loses focus and clicking on any tool has no effect. To regain focus the icon in the Windows Taskbar has to be clicked.
Please accept my sincere apology for the inconvenience. Please get in touch with us at any of the other support channels – https://helpx.adobe.com/support.html . Since this is not a generic issue that we can reproduce at our end, we will need someone to look into your machine to figure out what is going on here.