On the internals, I've read a few support cases that describe this behavior. What seemed to work to resolve this issue were the following items - NOTE - before attempting these steps ensure you are not using an offline license of ArcGIS Pro.
1. Run a repair of ArcGIS Pro
- Close all ESRI programs.
- Go to the Control Panel > Programs > Uninstall a program
- Right-click ArcGIS Pro > Uninstall/Change
- Navigate through the wizard and select the option to 'Repair'
- Next through the dialog until you Finish
- Launch ArcGIS Pro and attempt to reproduce the behavior. If the issue persists, proceed to the next step. If not, stop here.
2. Reset Esri folders on user profile
- Close all ESRI programs.
- Navigate to "C:\Users\%username%\AppData\Roaming"
*AppData folder is hidden by default. If AppData is not available, you need to click Organize > Folder and search options > View > Under "Hidden files and folders" > Check Show hidden files, folders and drives.
- Rename the Esri folder to Esri_Old.
- Navigate to "C:\Users\%username%\AppData\Local\ESRI"
- Rename the file ArcGISSettings.XML file to ArcGISSettings_old.xml
- Rename the folder ArcGISPro.exe_URL_(long alpha numeric string) folder to ArcGisPro.exe_url_old
3. Reset the Esri folder in the Registry.
*Important: These steps tell you how to modify the registry. Serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow the steps carefully or have your IT assist you.
- Go to windows Start menu and type 'regedit' in the search box and hit enter. This should open the Windows registry editor
- Once in the Registry Editor, navigate to the following directory (look on the left-hand panel of the window) HKEY_CURRENT_USER\Software.
- Rename the ESRI folder to ESRI_Old
Hope this helps resolve the issue!