In Maya 2018.5 I ran into the problem.

I get the message "out-of-core memory limit exceeded"
although Out-of-core was turned on, but for some reason it is not used or does not work.
I tested this on Maya 2018.5 on Octane v4.05-13.48 and 2020.1rc2-17.13-beta
I use ORBX to load the environment (the ...