So after quite some time with the phone reps, we solved the following problem...
After checking in online I could customize MBs and make FP+ resos. However, when getting to the confirm shipping address in the MB portion online, I would get an error message. It clearly states that if you live outside the US you can customize MBs but they will ship your MBs to your resort front desk for pick up upon check in. It then asks to verify your shipping address, which is your home address by default. If you click to confirm this you will get an error message. The only way around this is to change your shipping address to your resort's address. Then you can confirm shipping and move into customizing. After that everything should work fine.
After checking in online I could customize MBs and make FP+ resos. However, when getting to the confirm shipping address in the MB portion online, I would get an error message. It clearly states that if you live outside the US you can customize MBs but they will ship your MBs to your resort front desk for pick up upon check in. It then asks to verify your shipping address, which is your home address by default. If you click to confirm this you will get an error message. The only way around this is to change your shipping address to your resort's address. Then you can confirm shipping and move into customizing. After that everything should work fine.