Why does my WCF Service generate Array types when I explicitly set it to List?

I have been consuming a service for some time in development, and have been updating my service reference almost daily with no problems. Collection types have been set to generate as System开发者_Go百科.Collections.Generic.List in the Advanced options.

However, for no apparent reason, now when I update the Service Reference, it's generating Array types for all my collections! It is still configured to generate the List type, why is it all of a sudden going back to the Array type?? I'm using VS 2010..

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Here's the answer. A code change on the service was as follows: a class was marked as Abstract, and used in another class as List<AbstractClass>. Generating the service proxy on the client machine (EVEN WITH SVCUTIL.EXE) was forcing all of my list collections to be generated as Class[] instead of List<Class>. Removing the Abstract from the Class fixed everything and I am able to generate my service proxy from within VS and from the command prompt without issue.