Thanks for posting this, Hornby-Hunters. The distance limitation is fairly well known (it applies to my Oregon 650 as well as your GPSMAP 64), but there's been some uncertainty about the actual maximum distance involved. Now we know.
--Larry
I just bought a Garmin GPSMAP 64, and I ran into the same issue. But now I have a stupid question: How do I do a "Search Near" on the device? It is not mentioned in the manual. Thanks.