The info says that solo/ isolate mode can be used when baking high poly to low poly in order to hide all other objects. But in order to display both - high and low poly - I need to select them. Then, however, the baking option wont be accessible.
Am I doing it wrong?
No, you’re not doing anything wrong.
Unfortunately, something has changed in solo behavior - Stephane said he’s thinking about it again.
I had exactly the same question the day before yesterday 
The only thing that helps at the moment is to hide all other objects.
Yikes……
On web demo, both bake feature are now available with multi-selection.
All the selection is taken into account (visible or hidden doesn’t matter) and the main mesh only is getting baked.
My issue with the previous Solo behaviour is that it had a “hidden” state (mesh not selected but still solo’ed), and it wasn’t clear in the interface why some meshes were visible once you spent some time with solo ON (adding some mesh in the scene, undo/redo, etc).
Maybe I’ll add back the previous behaviour, but I want at least an indicator in the scene tree that says that something is stuck in solo.
Managing a large number of objects, especially when dealing with both high- and low-poly versions during the baking process, can be quite overwhelming. It would be incredibly helpful to have a system similar to Marmoset, where naming conventions like _high and _low are automatically recognized to streamline the process.
Alternatively, how about allowing the low-poly mesh to be set as a child of the high-poly mesh? Then, with a “Bake Parent Only” option enabled, the baking process could automatically focus on the parent object. This could significantly simplify workflow and reduce manual organization.
