If the download is not working properly, or you see white or blue squares on the mapscreen, it is likely that there are missing map tiles due to an interruption during your map pack download. Check the tile counts for each map pack are as follows.
MAP TILE COUNTS -
EOTOPO 2019
Base Pack: 5365
577K Pack: 58804
144K East Pack: 279,265
144K Central Pack: 254,047
144K West Pack: 347,448
If there are any anomalies, you will usually see the message Partially Downloaded and option to Download. Press Download to complete the installation of the missing tiles. If you don't see a Download option, or the Data Manager has frozen, close the app then reboot before trying again. To delete all downloaded map files in one go - go to ADVANCED and press CLEAR DB MAPS. This will reset the downloads for all map packs.
If you have problems with the map when ONLINE - simply zoom the map to refresh a new map tile.