Problem with Post Category Archive reverting to Page Category Archive

I have set up an Archive Layout in Themer and used the Post Module in the layout limiting the posts to be used from a single Category. Every time I choose the Location for the Layout to be applied to that category using Post Category Archive, Beaver Themer keeps reverting to a location of Page Category Archive and the Themer Layout is not properly applied. What am I doing wrong and how to I get the Post Category Archive location to stick without constantly reverting to Page Category Archive instead? I have tried multiple times and I keep getting the same results. In fact, the only way I can get the Archive Themer layout to stick is if I select All Archives as the location.