Just tested removing my "ExecStartPost=" line from the "[Service]" section and adding "Before=systemd-oomd.service" to the "[Unit]" section. It works as you said; now systemd-oomd starts after zram-config so problem is solved.
Just tested removing my "ExecStartPost=" line from the "[Service]" section and adding "Before= systemd- oomd.service" to the "[Unit]" section. It works as you said; now systemd-oomd starts after zram-config so problem is solved.