Markers for new users don't appear, existing users do.

Hello. Markers for new user accounts don't appear on the map/user on my installation. But the two user accounts that were present when I set the gmap system up appear fine, and if I change the placement of the marker it is immediately updated at its new location on the map. I see no difference between the user accounts and am really scratching my head on this one. I was originally using version 7.x-2.6+4-dev and updated to 7.x-2.6—the issue remains. Also tried setting up an additional user role with no affect. Regenerated marker cache several times. Cleared system cache. All modules and core are up-to-date. Hoping you can help. Thanks!