A couple of suggestions - if you have any mods installed, try removing them and then claim the new city. If you're claiming the new city from the main menu, try going in to one of your other cities, and claim it from the region view. Repair Game - in Origin, right-click SimCity icon and choose Repair Game. Use SimCity Recovery tool - Default location is Program Files (x86)\Origin Games\SimCity\SimCityRecovery, run SimCityRecovery.exe in Administrator mode.
Please shoot back a message if any of these work, would be helpful for others to know if there's a solution in there. Good luck!