Linux Ubuntu Resize disk, revered disk space before getting full to auto grow.
Issue : "internal Linux Escalation Engineers regarding this, they confirmed that is by design for Ubuntu VMs. The disk size will not auto grow once it is full before resizing from the portal. For the size to auto change, there will be some free space on the disk before resizing on the Azure portal." Suggestion: to avoid this issue again in the future, as a permanent solution would be great if your team can implement a default setup to reserved some space enough to be able for the VM to auto-grow the disk before is "out-of-space".