2.7 Circular reference in texture stack

This is a problem I used to be able to solve in the 2.6x cycle, but it seems to be cropping up again and the old solutions don’t seem to be working.

In the past I used to simply refer to this video for reference and made sure I followed all the steps, but that doesn’t seem to be doing it anymore.

Basicly I’m just trying to do a full render bake from one texture to another. Some of the UVs overlap in the UV layout (which I thought could have been the issue) but I spread them out and it makes no difference. The texture being baked to isn’t in my texture stack and the source texture doesn’t have any UVs assigned to it, so I’m at a bit of a loss with this one.

Blend file attached below, textures should be packed.
dicebox004.blend (1.09 MB)

Same here, when doing a full render bake Blender seems to switch to the source texture from any selected texture. Or something. Doesn’t work is all I can know.