After upgrading ArcGIS Pro to another version, the layer templates in the Layer Templates group appear empty as shown in the image below.
ArcGIS Pro is improperly upgraded where certain elements on the ribbon are affected. For example, this issue can occur due to overwritten files within folders while upgrading the application.
To resolve the issue, perform a soft reset by renaming the resource index folder of ArcGIS Pro in File Explorer.
Note: The AppData folder is hidden. Refer to Microsoft: Show hidden files for instructions to display hidden folders.