Can't create/adjust/delete a partition
I was able to fix it by getting the UUID for my disk and then run the following command:

corestorage revert UUID


You can get the UUID for your corestorage disk by passing corestorage list and then you will get something like this Logical Volume C51A83AC-321D-4B5F-A5D7-7713F8B36874. The part behind 'Logical Volume' is your UUID.