It works alright for me - I went to Northwind 1947, chose Annotate, and everything loaded fine.
First I got a 100% blank page, so I said "No" to all the questions.
Then when the next page had loaded, I went back to the vessels page, chose the same vessel - and I got the exact same page. Very nice!
I used my work computer, which has Windows 7 SP1 and Chrome 46.0.2490.71 - will test my personal Windows 10 laptop when I get home.
However, when I tested Firefox 38.0.5 on the same PC, the interface loaded fine but I got the blank page I had already done in Chrome.
Then after Firefox (not my default browser) finished updating itself to 41.0.1, I tried again - same thing.
So in other words, it looks like you should only use one browser for this new stuff.
Maybe you had a connection issue, Maikel? It took some time for the interface to finish loading for me - in both Firefox and Chrome.
For now, I'm sticking with Phase 3 anyway. I got things to finish here.