Found the same issue on 2018.1. Remove "hyper-v_fb" from the line to make it: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash video=1280x720"
Was able to change the res after this.
Type: Posts; User: serotonin
Found the same issue on 2018.1. Remove "hyper-v_fb" from the line to make it: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash video=1280x720"
Was able to change the res after this.