During the install (CUSTOM path), Disk Druid offered the setup of disk partitions. Once first DELETE and subsequent ADD/EDIT sequences occurred, the NEXT block was greyed out. Even when all available disk space was assigned, the NEXT block was still not made available. Using BACK or RESET buttons didn't fix the situation. Had to reboot system to recover.
There are a couple of conditions which have to be met for the "Next" button to light. One, there must be a root partition. Two, there must be a swap partition. That pretty much sums it up. If you have these two things, then you should be able to continue with the installation. Please reopen this bug if you continue to have trouble.