Isolate selected is available only in the IPR as a debugging feature. Rendering only selected objects is currently not implemented but it's on my todo list.
If you have just a few objects to render, you can use operators to mask out the rest. Here's a small example scene: matte_op.zip
The Torus object has a boolean User Data parameter called 'selected'. The operator adds a matte shader to all polymeshes which does not have 'selected' enabled.
Other option could be to write a script to go over all objects and change the matte flag based on selection.
Hey Peter,
is there an update on this? I´d need this as well and it would be super helpful to render parts only, if the asset had to be replaced with something else.
The 'Render Selected Objects' feature was implemented since, see the Advanced section of the render settings: https://help.autodesk.com/view/ARNOL/ENU/?guid=arnold_for_cinema_4d_ci_Main_ci_Advanced_settings_htm...
Otherwise you still have to use operators as stated below or a custom script.