Use of simple optimizer vs. multi-GPU optimizer

How severe does this issue affect your experience of using Ray?
- Medium: It contributes to significant difficulty to complete my task, but I can work around it.

Do people have any tips / tricks to getting the multi-GPU optimizer working? I have found that only the simple optimizer works for me, severely limiting performance on my machine for a given task (I can work around it by launching multiple Ray instances, but would like to improve the speed on a given one). It also says in the documentation that it is possible for the multi-GPU optimizer not to work, but the simple one seems to be deprecated, and I was wondering what the known issues with this were. Let me know if anyone else has had issues with the multi-GPU optimizer, and what you’ve done to fix it. Thanks very much!