Dark probe results in 2018.3

Hey! Probe-lit objects will use SH coefficients as opposed to lightmaps, so there might be slight visual differences between lightmapped and probe-lit objects.\

There are couple of ways you can mitigate it. One of the ways is to use mixed lighting mode for your directional light. In that case, you will have realtime direct contribution to both lightmapped and probe-lit objects.

Another solution would be to place more probes in your environment to increase sampling accuracy.

Also, make sure that you are using identical materials for both of your objects. Switching to linear color space should also help.

I've made a quick experiment using the same lighting setup as yours. The sphere on the left is probe-lit, while cube on the right is lightmapped. Notice how there's very little difference between the two.

 

This is a known issue with Auto LDA (lighting data asset), which had already been fixed in Unity 2018.3. One may to mitigate this would be to bake your lightmaps with Auto Generate disabled. After doing so, entering Play mode should preserve your lightmaps and ambient probes.

 

Tweaking Indirect Intensity and Albedo Boost sliders can definitely work, unless you want all your lighting in the scene to be PBR compliant. If that's the case, it is better to leave them at their default values.