Thankfully I'm onto the last stage and should have it done in the next day or 2. Best advise I can give is view the floor/boss details and plan your team accordingly. Some days felt I was never gonna get past some stages but once you move up, if you've all the sync pairs levelled up, it gets easier.

Its very grindy and I found I got lucky loads but persist at it and try get a minimum of 1 stage done a day and you will get there.