Use brackets around the selection
--cuda-devices [0,1]
Make sure you don't use it with --auto-detect
To understand better for myself; my 5 gpu's are all AMD's, and with your command I would set those first 2 as to use the Nvidia Cuda so disabling them AMD's, right?
Unfortunately it does not seem to work.
I couldn't get the brackets into the hiveos "disable gpu's" field; so added your command to the "Extra config arguments" field. Now it doesn't even load any gpu with TBM. Only the first 2 with TRM.
Maybe it's a hiveos bug.
I've also noticed they are still on 1.16 whilst you are already at 1.18.