As you said, there was a SIM contacts problem in Moto G. Lot users facing this problem after their Android KitKat software update.
Here are my suggestions on How to solve SIM contact issue on Moto G:
Try to import the SIM contacts, by going to Contacts and "Import/Export" option.
If it doesn't work, then:
You must install an independent third party application which can copy SIM contacts to phone memory.
Google Play Store provides many SIM management/contact management applications. Just try to download and import your contacts.