Ao bake result is dark

i use a image to create mask, so middle part is set as golden texture.

image

but when i bake it, only mask part ao is baked dark, the rest is baked normally.
what’s going on?.

i use simple bake addon

Any objects hidden for render or are blocking it from light?

no hidden object, and fold geometry, no flip faces. it seems ao reder is flip or ao distance is too large? i don’t know

it is not mask’s problem, i have delet texture, but get same result

Still not exactly sure what the problem is. Only he mask part of the mesh is baked? Maybe the others are baked too but its not as visible.