In the entire database?
IMatch maintains an automatic workflow category under "IMatch Workflow Categories > No GPS Data".
You can use this with the category filter and invert to see all files with GPS data in the current scope. Then press Ctrl+A.
You can also use a metadata filter for one of the GPS coordinates with the
has value option.
This shows all files with a value for the selected tag in the current scope. Then press Ctrl+A.
