Can confirm that transferring from the NA Datacenter to Omega on the EU server has allowed me to complete the instance. I literally had to leave everything I had on Jenova just to progress through this story quest, I know some might not want to do this, but I can can confirm this worked for myself, and 2 other previous NA players I met in Sirensong Sea also did this method. Just thought I'd share this, I'm heading out now, good luck everyone.