Steps to reproduce: 

1. Open a sample project with a basic web test and include a coded step. Close both the test and the code behind file from the UI. 

2. Open Project Settings and change the Namespace name.

3. Note that the project and test files are only marked as dirty. 

4. Compile the project. 

Expected result: Successful build

Actual result: Build fails with error that 'Pages' could not be found. 

NOTE: Open the code behind file and make any change within so that it could be marked as dirty. Compile again to get a successful build. 

Or keep the file open in the UI during changing the Namespace in the settings - this will update the files accordingly. 

If the code behind file is opened in Notepad++ it is clear to see that at the moment of step 4 the namespace in the file is still the old one and is reloaded if the file is changed and saved in the Test Studio UI.