EDIT: I think I solved my problem by adding it to the Option.txt file. I'm not entirely certain if this fixed the issue or it was fixed when I changed the advertised resolutions in sunshine.
Yeh, editing the options.txt will add/remove resolutions on driver initialise. SO disabling and enable the driver, uninstalling and installing or just restarting the device
EDIT: I think I solved my problem by adding it to the Option.txt file. I'm not entirely certain if this fixed the issue or it was fixed when I changed the advertised resolutions in sunshine.