Thanks for your feedback and information. I'm able to load a gpx via GSAK but only some caches are available (tried to filter on name etc). I imported the caches from 680t to GSAK and the caches that don't show on 680t are visible on the GSAK file. I used the same file to load to husband's Montana 650t and all the caches are available when I search. I also loaded the cache file via Garminexport macro as GGZ!! THANKS!! Garmin Helpdesk is misinformed (said only Garmin can load/use GGZ and that I should delete the entire GGZ folder). Unfortunately, the same caches are still not available 680t when I search.
The caches I cannot see on the 680t are approximately 100 miles away. I haven't found any map filters and I have not created any geocache filters. I'm not sure if I had satellite lock since I completed hard reset while attempting this loading process. Thanks again for all the info!