Strange.
To give it a try, I changed my firmware from v2.00 to v2.10 (etrex 30x)
CN Europe 2016.10 NTU had been installed in the past with v2.00, but removed it as I don't use it on the etrex.
After installing v2.10, I re-installed CN Europe 2016.10 NTU and it works fine.
Then I installed CN North America 2016.20 NT, for the very first time on the etrex.
This map never had been installed before, neither with v2.00, nor v2.10.
Also CN North America 2016.20 NT works fine.
Topo Germany v7 Pro and Spain v5 Pro also work fine with v2.10
Are you sure you did unlock your maps properly with the [Only registered and activated users can see links. ] gimgunlock version?
Perhaps the map-image files are damaged ? (do they work properly in BC ?)
Perhaps your SD-card is damaged ? (try another one)
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