By "geo tags", do you mean the GPS lat/long coordinates or the city/state/country provided by LR's reverse geocoding?
In my LR 5.6 / Mac OS 10.9, Synchronize Folder reads both changes to keywords and changes to GPS coordinates, provided the option Scan For Metadata Updates is selected.
If you're not observing that, provide more details about what you're doing including the version of LR and how you're changing the metadata outside of LR.