As previous altars such as the ones in the Overworld and Abyssal Wasteland, the altar creation procedure with the Dreadlands Necronomicon does not work at all in the Dreadlands despite using the Dreadland Cobblestone that is required, am I doing something wrong?

Are you using 1.9.4-pre-4 in 1.12? There was a change I forgot to take into account in the port, resulting in some of the blocks used for the ritual setup being swapped. Updating to any newer release fixes it.

Closing this now. This was addressed a couple of updates ago.