I've been waiting for over an hour now and im not sure why but phase 7 never will start, and if I summon a phase 7 wither it never opens a hole.

If you never formidibombed it won’t evolve until after it’s blown up. Otherwise patience is key, it can take a while (you can always mess with it’s evolution speed in the server config)

It stops growing at phase 5 or so when first spawned, you need to trigger the bomb on it and then re-awaken it to advance to 6 and 7, its mandatory