Go to “Volumes” and then “Block Devices”. For your 4TB volume, what is the label type? If it says “msdos”, as I said, you cannot have a “msdos” partition table and use more than 2TB. If it says “gpt” then you may have hit upon a bug.

If it says “msdos” then do the following:
– Remove any volumes, volume groups, physical partitions, etc. that you created on that disk.
– Open a command prompt
– Run “parted /dev/sda” (substitute the appropriate device name)
– Type “print” (you should see the total size of the disk and the label type)
– Type “mklabel gpt”
– Type “print” (to make sure that the label has changed)
– Type “q” (to quit)
– Close the command prompt

Back in the web admin, refresh the “Block Devices” page and see if it now shows a label of “gpt”. If it does, create your physical partition, volume group, etc. If it doesn’t, reboot.