Disk size does not match at all (ubuntu/VMWare)

Solution 1:

Well I managed to get it to extend the LV with

lvextend -l+100%FREE /dev/mapper/ubuntu--vg-ubuntu--lv -A n :)

It was the autobackup that blocked the LV to extend because it was so full. So -A n sets the autobackup to no in case somebody encounters the same problem.