Operating system: Windows-10-10.0.18362 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 417.35
Broken: version: 2.80 (sub 75), branch: master, commit date: 2019-07-29 14:47, hash: rBf6cb5f54494e
Short description of error
When a mesh has a modifier on it and is used as a bake target with a Cage object and that Cage object is in a different scene (but has the same modifier), the bake will fail reporting that the objects do not have the same number of sides. When the Cage and target are in the same scene it works as expected.
Also, separate to this issue but connected: The Cage object will have its Render visibility left disabled after bake (regardless of success or failure) when ever its not in the same scene.
Exact steps for others to reproduce the error
-Add a Cube, add a Mirror modifier to it.
-Create a new scene.
-Add a Cube and a Cone to the new scene.
-Give this Cube a Mirror modifier with the same default settings as the previous Cube.
-Give the Cube a material with an image texture target for the bake.
-Set Render to Cycles, open Bake panel and choose 'Selected to active' and then check the 'Cage' option.
-Pick the original Cube in the first scene as the Cage object.
-Select the Cone and holding shift select the Cube.
It will say that the cage is invalid as the objects have different number of sides. If you now check back in the first scene, the Cube there will have had its Render visibility turned off.
Now delete or disable for render the mirror modifier on the target cube and repeat the bake. It will now work, even though the cage still has the modifier (it should NOT work in this configuration). The Cage object will again have its Render visibility disabled regardless of its starting state.
I have attached a simple demowith three scenes:
1)base scene - has all objects in it and works as expected.
2)broken - has a Cube with mirror mod and a Cone with the Cube from scene 1 set as cage, shows error.
3)working - same scene as 2, but mirror mod is removed. Look at base scene after bake and see how the cage has been left hidden for render. Note that while this works, it shouldn't be working and should report that the meshs don't match!