Hello,
I am assuming you have the key installed as this is a premium feature. After that, the only reason I can think of is that you are saving the metadata to a sidecar file and not copying the sidecar file to the SD card. We can only embed metadata into JPGs at this time so if these files are any other file type, you must use sidecar files to save metadata. Please look at this link to fill in the details:
http://www.fstopapp.com/metadata/
Let me know how it goes.
Regards,
Jason Seelye
