‘Out of Darkness’ featured Fort Anaxes, a republic base that was abandoned after the Clone Wars. The Clone Wars untold Echo arc was supposed to take place on Anaxes and Skako Minor. Is Fort Anaxes the same place as Anaxes ?
My theory is that the Echo arc started on Fort Anaxes and then Rex and his team of clones went to other parts of Anaxes for their missions that lead them to Skako Minor.
Another thing is a concept art that is almost identical to a concept art used for Darth Maul Son of Dathomir, you can take a look at them below :