wordpress 5.5.1 en_au not listed as option for auto install

I have several websites on a server and gradually clicked the WordPress update button to update all of them to 5.5.1. I got half way down the list and have just noticed that the wordpress 5.5.1 en_au version is no longer listed. Only the US version is listed. Why would the localised AU version not be present anymore as an option (always used to be) and is the US version OK to be installed instead?