the version numbers get skipped often, version 319 might have been beta tested and found to have issues so its never been published.
You can do a manual install of the firmware you found on the installer site, you’ll have to download the firmware yourself onto your inverter dongle. The fact that you are not seeing the version on the portal suggests that it’s not been pushed out to everyone yet so you can either stay with what you have or upgrade to the latest. Its always worth being on the latest version, but if there isn’t fixes for something you need, no harm to remain on the latest mass rollout version