Nuvi 13xx and 14xx series (GCD File) software version 6.20 is of November 27, 2012-
No problems has been reported with this firmware, CNNAN unlocked works fine in new and old nuvis, I think it is your problem.
You can reverse to previous firmware, but I guess it wont solve the problem.
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the maps can be seen in the sys info page
Do you mean they are in Maps list? Do you have more than one map covering the same area? Do you get any error message starting nuvi?