It's never been supported to increase the datastore on the installation disk.
However, the web clients unfortunately don't block this option, and rather fail.
What I think is missing is just the file system expansion, i.e. these 3 commands (see link I posted earlier)
partedUtil fixGpt /vmfs/devices/disks/naa.644a842011ed7f0023dde11d08943acf- vmkfstools --growfs "
/vmfs/devices/disks/naa.644a842011ed7f0023dde11d08943acf:3" "/vmfs/devices/disks/naa.644a842011ed7f0023dde11d08943acf:3" - vmkfstools -V
If you have a support agreement with VMware you may have them double-ckech. In any case make sure that you have an up-to-date backup in case something unexpected happens!
André