When expired I contact Mojang support, useless as usual, they didn't respond with an actual response, with a reason why all of this is happening, they just say in a nutshell "ask Microsoft for the paying stuff". I call Microsoft support for a refund for my subscription and they immediately gave me, then I paid again, for a new whole month; now, the setting page of my realm says "Renew every 30 days" in the Duration section.
Try to ask for a refund and purchase again if you don't see "Renew every 30 days" in the Duration section.
When expired I contact Mojang support, useless as usual, they didn't respond with an actual response, with a reason why all of this is happening, they just say in a nutshell "ask Microsoft for the paying stuff". I call Microsoft support for a refund for my subscription and they immediately gave me, then I paid again, for a new whole month; now, the setting page of my realm says "Renew every 30 days" in the Duration section.
Try to ask for a refund and purchase again if you don't see "Renew every 30 days" in the Duration section.