We have encryption process to encrypt private fields as part of our release process. During the encryption, some private fields will be renamed, and some of the name might be invalid for serialization reflector. The error you have is one of the case.
However we do have flags to exclude import fields from encryption, that those fields can be proper serialize and deserialized.
We have to reproduce the issue before we can track down which field(s) needs to be excluded from encryption.
Would like to double check are you having issue with GoogleMapsLayer or GoogleMapsOverlay on the serialization?