Linker Error when compiled with Atmel Studio 7

[BonShaw1]

I have implemented the streaming parser in an Arduino sketch and it works great. In an effort to get more debugging capabilities I am using AS7 v7.0.1931. The sketch compiles just fine but the linker fails. The error is "undefined reference to 'vtable for Listener'. Both Parser.h and Parser.cpp are present as when using the Arduino IDE. Unfortunately, the linker gives no other hint as to the resolution to this issue. If I comment out "Listener listener;" and any reference to Listener then everything compiles normally. Any help is welcome!