To try and resolve your issue, try merging your project into a blank new project. To do this:
1. In NVivo, create a blank new project.
2. Click the Import tab and the click the Project icon.
The 'Import Project' dialog box appears.
3. Click Browse and navigate to and select your project file from the Desktop.
4. Click Import.
Once the import finishes, see if this issue is resolved in this new project file, which contains your entire project data.
If the issue still persists, can you please send us the project file by submitting a support request at https://qsrinternational.com/nvivo/contact-us/customer-support ?