Hi @Joshua Smith ,
VS/SSDT preview render is not the same as SSRS server report render.
It be could something wrong with VS previewer. It is quite rare and hard to say what happens within VS for this scene.
Honestly we from SSRS side cannot really debug VS extension. I would suggest you to use newest version of SSDT. As I know it should be 17.4 for VS 2015. See : SSDT for Visual Studio (VS) 2015
Regards,
Joy
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