@ AnaSugar: do you see your GPU listed in the info bar in viewport?
Check to have updated to the latest Catalina 10.15.6 version, to have the latest Apple Metal driver.
@ madebo: under Catalina, only AMD Navi and Vega are supported, but with the upcoming Mac Os 11 Big Sur, with new Apple Metal driver, OctaneX is going to also support Intel Skylake, and AMD Polaris GPUs.
Unfortunately, the first MacBook Pro with Intel Skylake CPU should be from 2016, so I’m not sure if your Mac will be supported
Note that you can already add one or more of the supported AMD GPUs (like Radeon VII or 5700XT) via eGPU box with Thunderbolt 3, natively supported in both Catalina and Big Sur.
@ Stathman: in OctaneX, AI Denoiser is performed by the CPU, not the GPU, so it is a bit slower to calculate, but it does not affect GPU memory, and does not need to select a GPU for it.
Note that you need a CPU from 2015 or newer, to have the necessary instructions to perform AI denoiser.
About c4doctane PR1, for stability, please avoid to use the Node.Graph to edit your materials as much as possible, and prefer to use the Attribute Editor window for now.
Happy Mac GPU Rendering,