Hello ,Nichlas

Thank you for contacting us with detailed description of the encountered misbehavior. I tested the same on my end and luckily, managed to reproduce it. This is why I converted the current thread to a bug report in our public feedback portal - the public item can be found here. The issue will be investigated by the development team and a fix will be applied. 

However, this will take some time until is published live in the upcoming Test Studio releases. Though the good news is that we found a workaround to ease the project maintenance until the root cause is identified. Please, read below the workflow you can follow: 

1. Open the project in Test Studio and the project's root folder in the Windows Explorer. 
2. Select the test you need to rebind.
3 .From the Test file context menu select to Remove the Data Binding. Save the changes. 
4. Bind the test to the desired sheet in the file. Save the changes. 
5. At this stage, you shouldn't be able to manage the excel file through Test Studio. 
6. Exit Test Studio completely. 
7. In the project's root folder open the Data sub-folder and open the file, used to rebind the test. Once opened from the Windows Explorer, it should work fine. 
8. Close the excel file, open the project again and navigate to the data files Manage wizard. You should be able to manage the file within Test Studio as well. 

It seems that Test Studio locks the file somehow and thus it cannot be edited anymore. So I hope the above steps will work for you as well. However, in case there is any discrepancy in the behavior on your end, please let me know. 

Thank you for your understanding once again. 

Regards,
Elena Tsvetkova
Progress Telerik