How am I supposed to get the 8th badge if the 7th badge only allows me to get up to lvl 40, but the mind badge quest requires lvl 45?
The mind badge quest does not require you to be level 45, I've obtained the 8th badge myself and I'm still only level 41. Perhaps you are thinking about a different quest?
I'm going to go ahead and say you can just ignore that, just talk to Gordon on Occult island at these co-ordinates: X: 1769 / Y: 37 / Z: 124 and you'll be able to start the quest. The above has been reported and will hopefully be fixed soon .